U.S. patent application number 09/848073 was filed with the patent office on 2001-11-15 for endodontic systems and methods for preparing upper portions of root canals with increasingly rigid files.
This patent application is currently assigned to Ultradent Products, Inc.. Invention is credited to Riitano, Francesco.
Application Number | 20010041324 09/848073 |
Document ID | / |
Family ID | 46257725 |
Filed Date | 2001-11-15 |
United States Patent
Application |
20010041324 |
Kind Code |
A1 |
Riitano, Francesco |
November 15, 2001 |
Endodontic systems and methods for preparing upper portions of root
canals with increasingly rigid files
Abstract
A root canal is sequentially cleaned in sections from the crown
to the apex by dividing it into three sections including an
operative coronal portion, an operative middle portion and an
apical portion. The pulp material is then sequentially removed from
the portion of the root canal above the apical portion of the root
canal with a set of instruments. The apical portion is then
optionally cleaned with another set of instruments. Another
optional set of instruments can also be used to improve the access
into the apical portion such that irrigants can be delivered to the
apical portion.
Inventors: |
Riitano, Francesco;
(Soverato, IT) |
Correspondence
Address: |
Rick D. Nydegger
WORKMAN, NYDEGGER & SEELEY
1000 Eagle Gate Tower
60 East South Temple
Salt Lake City
UT
84111
US
|
Assignee: |
Ultradent Products, Inc.
|
Family ID: |
46257725 |
Appl. No.: |
09/848073 |
Filed: |
May 3, 2001 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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09848073 |
May 3, 2001 |
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09736729 |
Dec 14, 2000 |
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09848073 |
May 3, 2001 |
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09753981 |
Jan 3, 2001 |
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09753981 |
Jan 3, 2001 |
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09536821 |
Mar 27, 2000 |
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09536821 |
Mar 27, 2000 |
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09492566 |
Jan 27, 2000 |
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6217335 |
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09492566 |
Jan 27, 2000 |
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09325035 |
Jun 3, 1999 |
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6059572 |
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09325035 |
Jun 3, 1999 |
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09014763 |
Jan 28, 1998 |
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6045362 |
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09014763 |
Jan 28, 1998 |
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08885906 |
Jun 30, 1997 |
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5775904 |
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08885906 |
Jun 30, 1997 |
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08656988 |
Jun 6, 1996 |
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5642998 |
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Current U.S.
Class: |
433/102 ;
433/224; 433/81 |
Current CPC
Class: |
A61C 5/42 20170201; A61K
6/54 20200101; A61C 19/003 20130101; A61K 6/52 20200101; A61K 6/54
20200101; C08L 33/00 20130101; A61C 1/003 20130101; A61K 6/54
20200101; C08L 33/00 20130101; A61C 5/50 20170201 |
Class at
Publication: |
433/102 ; 433/81;
433/224 |
International
Class: |
A61C 005/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 6, 1995 |
IT |
RM95A000377 |
Claims
What is claimed and desired to be secured by United States Letters
Patent is:
1. A method for cleaning the operative coronal portion and the
operative middle portion of an operative root canal of a tooth, the
method comprising: exposing the root canal by removing a portion of
the tooth at a crown thereof and by removing the top of the pulp
chamber; obtaining a set of first endodontic instruments wherein
each instrument has a file with an abrading portion for removing
pulp material, each file having a length corresponding to at least
the combined length of the operative coronal portion and the
operative middle portion; removing and cleaning essentially all
pulp material from the operative coronal portion and the operative
middle portion by sequentially introducing the files of the
instruments in the set of first endodontic instruments into the
operative middle portion and then flexing each file such that the
abrading portion of each file is urged against root canal surfaces
within the operative middle portion as each instrument is rotated
and moved in a cleaning motion in conformance with the anatomical
shape of the operative middle portion by following the contours of
the operative middle portion as a guide for movement of each
instrument, and without significantly extending the file of each
instrument into the apical root portion, wherein each sequentially
introduced file has greater rigidity than the previously introduced
file along at least an upper part of the abrading portion of each
file to enable each sequentially introduced file to more rapidly
and aggressively clean than the previously introduced file.
2. A method as defined in claim 1, wherein following the contours
of the operative middle portion involves moving each instrument
around the perimeter of the operative middle portion of the
operative root canal.
3. A method as defined in claim 1, wherein following the contours
of the operative middle portion involves moving each instrument
along a side of the operative middle portion of the operative root
canal such that each instrument generally has more than one center
of motion during the step of removing and cleaning essentially all
pulp material from the operative middle portion.
4. A method as defined in claim 1, wherein each file of each
instrument in the set of first endodontic instruments comprises has
a tip opposite a top end, and wherein the files of all of the
instruments in the set of first endodontic instruments have
essentially the same tip diameter while having distinct top end
diameters to enable the files to be sequentially introduced into
the operative middle portion such that each successive file has a
greater top end diameter than that of the preceding file.
5. A method as defined in claim 1, wherein each file of each
instrument in the set of first endodontic instruments has a tip
opposite a top end, and wherein the files of all of the instruments
in the set of first endodontic instruments have distinct tapers to
enable the files to be sequentially introduced into the operative
middle portion such that each successive file has a greater taper
than that of the preceding file.
6. A method as defined in claim 1, wherein the file of each
instrument in the set of first endodontic instruments extends from
a handle.
7. A method as defined in claim 1, further comprising the step of
determining the working length of the operative root canal to
select an appropriate instrument for removing and cleaning
essentially all pulp material from the operative coronal portion
and the operative middle portion.
8. A method as defined in claim 1, further comprising the step of
positioning at least one stop on the file of each instrument in the
set of first endodontic instruments sequentially introduced into
the operative middle portion.
9. A method as defined in claim 1, further comprising the step of
minimizing obstructions in the operative root canal before removing
and cleaning essentially all pulp material from the operative
middle portion such that instruments can be inserted in the
operative middle portion in a relatively straight manner.
10. A method for anatomical cleaning of the operative coronal
portion and the operative middle portion of an operative root canal
in a tooth, the method comprising: exposing the root canal by
removing a portion of the tooth at a crown thereof and by removing
the top of the pulp chamber; obtaining a set of first endodontic
instruments wherein each instrument has a file that extends from an
end means for grasping and operatively moving the file, wherein the
file has an abrading portion for removing pulp material that
extends from a tip to a top end of the abrading portion, and
wherein each file has a length corresponding to at least the
combined length of the operative coronal portion and the operative
middle portion; removing and cleaning essentially all pulp material
from the operative coronal portion and the operative middle portion
by sequentially introducing the files of the instruments in the set
of first endodontic instruments into the operative middle portion
such that each successive file has an abrading portion with a
greater top end diameter than that of the preceding file, and then
flexing each file such that the abrading portion of each file is
urged against root canal surfaces within the operative middle
portion as each instrument is rotated and moved in a cleaning
motion in conformance with the anatomical shape of the operative
middle portion by following the contours of the operative middle
portion as a guide for movement of each instrument, without
significantly extending the file of each instrument into the apical
root portion, and wherein at least the top end of each abrading
portion of each sequentially introduced file applies greater force
against the root canal surfaces than the previously introduced file
to enable each sequentially introduced file to more rapidly and
aggressively clean than the previously introduced file.
11. A method as defined in claim 10, wherein following the contours
of the operative middle portion involves moving each instrument
around the perimeter of the operative middle portion of the
operative root canal.
12. A method as defined in claim 10, wherein following the contours
of the operative middle portion involves moving each instrument
along a side of the operative middle portion of the operative root
canal such that each instrument generally has more than one center
of motion during the step of removing and cleaning essentially all
pulp material from the operative middle portion.
13. A method as defined in claim 10, wherein the files of all of
the instruments in the set of first endodontic instruments have
essentially the same tip diameter.
14. A method as defined in claim 10, wherein the end means for
grasping and operatively moving the file is a handle.
15. A method as defined in claim 10, further comprising the step of
determining the working length of the operative root canal to
select an appropriate instrument for removing and cleaning
essentially all pulp material from the operative coronal portion
and the operative middle portion.
16. A method as defined in claim 10, further comprising the step of
positioning at least one stop on the file of each instrument in the
set of first endodontic instruments sequentially introduced into
the operative middle portion.
17. A method as defined in claim 10, further comprising the step of
minimizing obstructions in the operative root canal before removing
and cleaning essentially all pulp material from the operative
middle portion such that instruments can be inserted in the
operative middle portion in a relatively straight manner.
18. An endodontic instrument system adapted for anatomical cleaning
of the operative coronal portion and the operative middle portion
of an operative root canal in a tooth, the endodontic instrument
system comprising: a set of first endodontic instruments configured
for sequential use in the operative middle portion of an operative
root canal to anatomically clean essentially all pulp material from
the operative middle portion without significantly extending into
the apical root portion, each instrument in the set including a
file having a length corresponding to at least the combined length
of the operative coronal portion and the operative middle portion
in order to remove pulp material from essentially all of the
operative middle portion of the operative root canal, the file
having an abrading portion adapted for removing pulp material
through abrasive action as the file is rotated, the abrading
portion being located on the file and extending between a tip to a
top end along at least most of the file, the file being able to
flex such that the abrading portion is urged against root canal
surfaces while the file is rotated and moved in a cleaning motion,
thereby enabling contours of the operative middle portion to be
used as a guide for movement of the file in conformance to the
anatomical shape of the operative middle portion while effecting
removal and cleaning of pulp material from essentially all of the
operative middle portion, wherein the file of each instrument in
the set of first endodontic instruments has sufficient rigidity to
apply pressure against the root canal surfaces via the abrading
portion as each file is flexed to urge the abrading portion against
root canal surfaces and as each file is simultaneously moved in a
cleaning motion, and wherein each sequentially introduced file has
greater rigidity than the previously introduced file along at least
an upper part of the abrading portion of each file to enable each
sequentially introduced file to more rapidly and aggressively clean
than the previously introduced file, and a handle connected to each
file opposite from the tip, the handle being configured to enable a
user to operatively move the file in an abrasive action while
bending and flexing the file within the operative middle portion of
the operative root canal.
19. An endodontic instrument system as defined in claim 18, wherein
the file of each instrument in the set of first endodontic
instruments has adequate resilience to avoid being substantially
deformed as each file is flexed to urge the abrading portion
against root canal surfaces and as each file is simultaneously
moved in a cleaning motion.
20. An endodontic instrument system as defined in claim 18, wherein
the file of each instrument in the set of first endodontic
instruments is configured to enable a practitioner to move the file
around the perimeter of the operative middle portion of the
operative root canal.
21. An endodontic instrument system as defined in claim 18, wherein
the file of each instrument in the set of first endodontic
instruments is configured to enable a practitioner to move the file
along a side of the operative middle portion in a manner such that
the tip does not remain primarily in one position as the operative
middle portion is cleaned.
22. An endodontic instrument system as defined in claim 18, wherein
the file of each instrument in the set of first endodontic
instruments has essentially the same length.
23. An endodontic instrument system as defined in claim 18, wherein
the files of all of the instruments in the set of first endodontic
instruments have essentially the same tip diameter while the
abrading portions have distinct top end diameters to enable the
files to be sequentially introduced into the operative middle
portion such that each successive file has an abrading portion with
a greater top end diameter than that of the preceding file.
24. An endodontic instrument system as defined in claim 18, wherein
the abrading portions of the files of all of the instruments in the
set of first endodontic instruments have distinct tapers to enable
the files to be sequentially introduced into the operative middle
portion such that each successive file has an abrading portion with
a greater taper than that of the preceding file.
25. An endodontic instrument system as defined in claim 18, further
comprising a stop configured to be positioned on one of the files
of the first endodontic instruments in order to limit insertion of
the file into the operative coronal portion and the operative
middle portion without substantially extending into the apical
portion.
26. An endodontic instrument system adapted for anatomical cleaning
of the operative coronal portion and the operative middle portion
of an operative root canal in a tooth, the endodontic instrument
system comprising: a set of first endodontic instruments configured
for sequential use in the operative middle portion of an operative
root canal to anatomically clean essentially all pulp material from
the operative middle portion without significantly extending into
the apical root portion, each instrument in the set including a
file having a length corresponding to at least the combined length
of the operative coronal portion and the operative middle portion
in order to remove pulp material from essentially all of the
operative middle portion of the operative root canal, the file
having an abrading portion adapted for removing pulp material
through abrasive action as the file is rotated, the abrading
portion being located on the file and extending from a tip to a top
end along at least most of the file, the file being able to flex
such that the abrading portion is urged against root canal surfaces
while the file is rotated and moved in a cleaning motion, thereby
enabling contours of the operative middle portion to be used as a
guide for movement of the file in conformance to the anatomical
shape of the operative middle portion while effecting removal and
cleaning of pulp material from essentially all of the operative
middle portion, wherein the files of all of the instruments in the
set of first endodontic instruments have the same length and
essentially the same tip diameter while the abrading portions have
distinct top end diameters to enable the files to be sequentially
introduced into the operative middle portion such that each
successive file has an abrading portion with a greater top end
diameter than that of the preceding file, and wherein each
sequentially introduced file has greater rigidity than the
previously introduced file along at least an upper part of the
abrading portion of each file to enable each sequentially
introduced file to more rapidly and aggressively clean than the
previously introduced file, and a handle connected to the top end
of the file such that movement of the handle also moves at least
the top end of the file along a common axis with the handle, the
handle being configured to enable a user to operatively move the
file in an abrasive action while flexing the file within the
operative middle portion of the operative root canal.
Description
RELATED APPLICATIONS
[0001] This application is a continuation-in-part of U.S. patent
application Ser. No. 09/736,729 entitled Endodontic Sealing
Compositions and Methods for Using Such Compositions which was
filed on Dec. 14, 2000. This application is also a
continuation-in-part of U.S. patent application Ser. No. 09/753,981
entitled Endodontic System and Methods for the Anatonical,
Sectional and Progressive Corono-Apical Preparation of Root Canals
with Dedicated Stainless Steel Instruments and Dedicated
Nickel/Titanium Instruments which was filed on Jan. 3, 2001. Ser.
No. 09/753,981 is a continuation-in-part of U.S. patent application
Ser. No. 09/536,821 entitled Endodontic Systems and Methods for the
Anatomical, Sectional and Progressive Corono-Apical Preparation of
Root Canals With Instruments Utilizing Stops which was filed on
Mar. 27, 2000. Ser. No. 09/536,821 is a continuation-in-part of
U.S. patent application Ser. No. 09/492,566 entitled Endodontic
Systems and Methods for the Anatomical, Sectional and Progressive
Corono-Apical Preparation of Root Canals with Minimal Apical
Intrusion which was filed on Jan. 27, 2000. Ser. No. 09/492,566 is
a continuation-in-part of U.S. patent application Ser. No.
09/325,035 which was filed on Jun. 3, 1999 and is entitled
Endodontic Methods for the Anatomical, Sectional and Progressive
Corono-Apical Preparation of Root Canals with Three Sets of
Dedicated Instruments. Ser. No. 09/325,035 issued as U.S. Pat. No.
6,059,572. Ser. No. 09/325,035 was filed as a continuation-in-part
of U.S. patent application Ser. No. 09/014,763 which was filed on
Jan. 28, 1998 and is entitled Endodontic Methods for Progressively,
Sectionally and Anatomically Preparing Root Canals with Specific
Instruments for each Section having Predetermined Working Lengths.
Serial No. 09/014,763 issued as U.S. Pat. No. 6,045,362. Ser. No.
09/014,763 is a continuation-in-part of U.S. patent application
Ser. No. 08/885,906 which was filed on Jun. 30, 1997 and issued as
U.S. Pat. No. 5,775,904. Ser. No. 08/885,906 is a continuation of
U.S. patent application Ser. No. 08/656,988 which issued as U.S.
Pat. No. 5,642,998. U.S. Pat. No. 5,775,904 and U.S. Pat. No.
5,642,998 are both entitled Endodontic Instrument for Rapid
Mechanical Widening of the Canal Mouth and Specification of the
First Two-Thirds. Priority of U.S. Pat. No. 5,642,998 is based on
Italian Patent Application No. RM95A000377 which was filed on Jun.
6, 1995. For purposes of disclosure of the present invention, each
of the foregoing applications is incorporated herein by specific
reference.
BACKGROUND OF THE INVENTION
[0002] 1. The Field of the Invention
[0003] The present invention is related to the field of
endodontistry. More particularly, the invention is related to
systems and operating methods for the preparation of root canals
for obturation. The systems and methods involve the use of at least
instruments which are dedicated for specific purposes in the
inventive methods and systems and are designed for minimal
intrusion into the apical portion.
[0004] 2. The Relevant Technology
[0005] To preserve a tooth with a pulp that is diseased or is
potentially diseased, it is generally necessary to remove as much
of the pulp material as is possible from the pulp canal of the
tooth, to shape the root canal(s) without excessively weakening the
root canal walls, to prevent or minimize the presence of bacteria
through the use of irrigants and dressings, and lastly, to clean
the walls of the root canal(s) by removing the smear layer created
during instrumentation of the root canal(s). These steps are all
done to prepare the root cavity for sealing or obturation which
involves filling the root canal with biocompatible materials, such
as gutta percha, before the pulp cavity is sealed, thereby
promoting the healing and functional recovery of the tooth. This
procedure is referred to as root canal therapy.
[0006] As indicated hereinabove, root canal preparation involves
pulp removal, cleaning of the root canal walls and shaping of the
canal walls. This is typically achieved through a guided procedure
with the use of instruments which are moved either manually,
mechanically or by combinations thereof These instruments are files
or bits that are configured to bore and/or cut. Mechanical
instrumentation can be achieved through the use of endodontic
handpieces coupled to instruments such as files. The endodontic
handpieces can impart rotational motion to a file, reciprocal
motion by alternately rotating a file clockwise and
counterclockwise, sonic movements or ultrasonic movements.
[0007] With regard to operating procedures, there are two basic
methods from which all of the canal-preparation techniques can be
derived. These methods have been interpreted by various authors in
an operational context and also in terms of the instrumentation.
The primary conventional systems and methods for removing pulp
material from the root canal of a tooth are the apico-coronal
(step-back) technique and the corono-apical (crown-down) technique.
Although these conventional cleaning techniques both rely generally
on sequential increases in the diameter of instruments inserted
into the root canal. The step-back technique involves the
sequential use of instruments by first inserting an instrument all
the way down to the apex of the root canal and then using
progressively larger files to clean the root canal. So the
step-back technique involves cleaning the root canal from the apex
toward the crown. The crown-down technique uses a set of files that
are inserted sequentially further and further into the root canal
until reaching the apex and then instrumenting along the entire
length of the root canal after the apex has been reached. Each
technique has its own unique benefits and disadvantages.
[0008] In the step-back technique, each file that is sequentially
used in the root canal has a larger tip diameter and a larger
diameter at the top of the file. First, a series of instruments are
inserted all the way to the apex that are increasingly larger until
the apical portion is cleaned Then the remainder of the canal above
the apical portion is cleaned and tapered by using a series of
instruments that are successively larger and shorter. With each
increase in diameter, the rigidity increases and the flexibility of
the files decreases. As a result, it is not possible for the files
to be moved in a manner that enables them to adjust to or to follow
the contours of the perimeter surfaces of the root canal. This
reduced flexibility also increases the likelihood that the files
will fail to contact some portions while removing too much of the
surrounding dentin in some areas through excessive abrasion and
resulting in overthinning of the walls.
[0009] Not only is the completeness effected by the use of a set of
files wherein each file is larger and more rigid than the preceding
file but the ability to safely move the file within the canal is
also limited. More particularly, the increasing rigidity results in
decreased ability to negotiate the curves in the canal. Significant
problems that can result from inserting increasingly rigid files
and also from initially inserting a file all the way down to the
apex includes laceration and transportation of the apical foramen,
as well as misdirection and perforation of the wall.
[0010] The apex can be perforated by extrusion of the infected
material through the apex due to the force exerted by the file on
the material as the file is pushed downward to reach the apex. As a
result, the periapical region can be invaded and contaminated. The
potential for extruding infected material through the apical
foramen of a necrotic tooth during the initial insertion of a file
instrument all the way down to the apex is a particular
disadvantage of the step-back technique. Another disadvantage is
that the procedure has identical steps for working in either
necrotic or vital root canals. In addition to exposing the tissue
surrounding the tooth to the infected material, apical perforations
may allow irrigants, filling or obturating material to flow out of
the apex. Such apical perforations, as well as wall perforations,
may delay tooth healing and may compromise the outcome of the
therapy.
[0011] Perforations can also occur due to a failure to maintain a
proper working length of the instrument during the procedure. As
the canal is widened, curvatures are straightened thereby
decreasing the required working length needed for the instrument to
work. To properly determine the appropriate working length, many
radiographs must be taken throughout the operation as the canal is
continuously being modified, which alters the length. The time
required to obtain the x-ray photographs or images and to adjust
the working length of the instruments by repositioning the stops
can result in a lengthy process. The step-back technique is also
time intensive because a large number of instruments are required
to complete the root canal therapy.
[0012] Another problem is the formation of ledges which can occur
when a practitioner attempts to insert a file as far as the apex
and the file is too inflexible to properly curve with the root
canal or move around a protrusion. When a file is too inflexible to
curve or flex as needed and is halted prematurely, the downward
pressure exerted on the file, in conjunction with the tendency of
the file to straighten itself, causes the tip of the file to dig
into the side of the root canal and form a ledge. Such ledges are
difficult to bypass; and if the ledge occurs very close to the
apex, the ledge may give the practitioner the mistaken impression
that the apex has been reached.
[0013] The crown-down technique was developed for several reasons.
It was desired to shape the canal "conically" so as to keep the
diameter of the foramen as straight as possible. The crown-down
technique was also developed to prevent the discharge of septic
material or obturation material from the apex after the initial
canal-preparation step and to prevent subsequent vertical
condensation due to the vertical pressure used to obturate the
canals with heated gutta-percha. Additionally, the crown-down
technique was intended to reduce the number of instruments utilized
compared with the step-back technique. However, as discussed
hereinbelow, significant potential problems may inherently result
from use of the crown-down technique.
[0014] The crown-down technique generally involves the use of a set
of file instruments that are incrementally inserted further and
further into the root canal until reaching the apical portion. A
file is first used that is sufficiently large that it binds near
the top of the root canal. Then an incrementally smaller file is
used so that it binds further down in the root canal. The files
that are sequentially used may be incrementally longer or the files
may have the same length and be further inserted into the root
canal due to their increased narrowness. Once the root canal has
been sequentially cleaned along its entire length down to the apex,
then a file is inserted down to the apex that it capable of
abrading against all of the surfaces of the root canal to eliminate
the stepped configuration that has been created. Root canal
cleaning procedures that are referred to as crown-down
methodologies also often involve the use of a series of instruments
after reaching the apex that extend to the apex and have an
increasingly larger tapers to finish cleaning and shaping the root
canal.
[0015] One example of the operational deficiency of the crown-down
method lies in its association with instruments made of
nickel/titanium Based on the greater flexibility of files formed
from nickel/titanium compared with files formed from steel,
proponents of the crown-down method in conjunction with
nickel/titanium files assert that such files can better follow the
curvatures of a root canal. Additionally, it has been asserted that
such files are more likely to stay in the center of the root canal,
thereby decreasing the likelihood of ledging or perforating the
root canal walls. The ability of a nickel/titanium file to stay in
the center is not necessarily desirable, in view of the morphology
and perimetrical variety of root canals, and particularly the upper
two-thirds of root canals which are typically laminar. In fact when
rotation is imparted to an instrument that stays in the center of
the canal, the file instrument works simultaneously and
indiscriminately on all of the walls within reach of the file.
Since root canal walls do not have equal thicknesses in all
directions and at all different points along a root canal, some
walls can be overthinned or perforated, while other walls remain
untouched.
[0016] Moreover, because nickel/titanium files are more flexible
than steel files, they tend to follow the path of least resistance
and therefore cannot be used, in the same way as steel files, to be
applied actively and intentionally by the operator. As a result,
even when the operator knows the thickness of a particular portion,
such as an interference or obstruction which the operator desires
to rectify or straighten, the operator lacks the freedom to
aggressively drive the file as needed and clean the portions that
are difficult to reach. Accordingly, when a nickel/titanium file is
used to clean a non-cylindrically shaped root canal, the file moves
only at the center of the canal and/or the area of least resistance
and fails to remove all of the necrotic tissue.
[0017] Some problems encountered in application of crown-down
methodologies include overthinning of root canal walls, perforation
of a root canal wall, excessively weakening of the walls of the
tooth or a failure to fully contact all of the canal walls. These
problems can be easily caused by the passive, self-guiding use of
nickel/titanium files, particularly when utilizing instruments with
progressively larger tapers in the transition from the first
instrument to the next one in the set.
[0018] Overthinning can occur due to the indiscriminate thinning of
the walls of the root canals by maintaining a file instrument in a
central location during working rotation. Such overthinning can
have devastating results. The inability to adequately direct a file
used in accordance with the crown-down technique based on the
practitioner's knowledge of the relative thicknesses of the
portions of canal walls is a significant disadvantage of the
technique.
[0019] Lateral perforation results from the formation of a borehole
that increases in size until a hole is formed in the side of the
root canal through the dentin and cementum around a root canal.
Similarly, dangerous overthinning may occur when the borehole
increases in size such that it extends into the cementum or very
close to the cementum but has not yet created a hole in the side of
the root canal then the root canal. Such lateral perforations and
areas and that have been overthinned may be obscured from the x-ray
due to concavities or curvatures in the root canal. As a result,
the practitioner may not realize that the borehole has a formed a
hole in the side of the root canal or extends into the cementum and
may therefore mistakenly conclude that the root canal treatment has
been successful. Infective bacteria that remained in the root
canal, perhaps in the portions that were not contacted with the
files, as well as toxins produced by the bacteria may then permeate
through the cementum and cause infection or other
complications.
[0020] An example of a cross-section of a laminar-type root canal
cleaned by the crown-down technique which may result in successful
root canal therapy since the instrumentation has not resulted in a
perforation and the cementum has not been exposed is shown in FIG.
15D of U.S. Pat. No. 6,045,362. Although, problems such as
perforations or overthinning have been avoided, FIG. 15D shows that
large portions of the root canal remain untouched despite the
change in morphology through the formation of large borehole. Note
that the change in the morphology of the canal shown in FIG. 15D of
U.S. Pat. No. 6,045,362 resulting from crown-down technique
instrumentation occurs due to drilling in a passive, circular
manner, especially when instruments are used having gradual and
progressive tapers. The failure to contact significant portions of
a root canal while forming a large borehole in a root canal is a
very typical result of the crown-down technique since most root
canals can be characterized as a laminar-type root canal.
[0021] It would be preferable to avoid the risk posed by failing to
contact significant portions of the root canal. Since the
practitioner is prevented from removing and essentially all pulp
material, the practitioner cannot be assured of the reliability of
the treatment. Additionally, the practitioner may not suspect that
the working instruments have failed to contact every segment of the
root canal since the canal has been instrumented from its top to
its apex. Use of a set of files with increasingly greater tapers
further contributes to a potentially incorrect conclusion that
cleaning by such a conventional process has resulted in removing
all material from the root canal. Further, the x-ray view of the
tooth, as with the step-back technique, may give the incorrect
impression that the root canal had been cleaned. It should also be
remembered that while rotation of a set of passively actuated
files, in the center of the canal, especially those with
increasingly greater tapers, in accordance with the crown-down
technique, may yield a configuration as shown in FIG. 15D of U.S.
Pat. No. 6,045,362 and result in successful root canal therapy,
there is a significant hazard of forming lateral perforations and
overthinning due to the passivity of the instruments when linked to
canal diameters and wall thicknesses that are still statistically
unknown.
[0022] As in the configuration shown in FIG. 15D of U.S. Pat. No.
6,045,362, the configuration shown in FIG. 15E of U.S. Pat. No.
6,045,362 may also result in successful root canal therapy--but
only for canals of the wholly tubular type. Although, the borehole
does not extend through the dentin and into the cementum, the
diameter of the preparation or borehole is nevertheless
significantly larger than that of the original root canal was. The
excessive thinning of the dental wall may result in significantly
weaken the resistance of the walls to the stress of chewing, and
may also cause a fracture of the root.
[0023] From the above discussion, it is clear that the actual
morphology of the canals is not sufficiently considered when using
the crown-down technique. More particularly, when files are used
with successively larger tapers, each file, if actuated passively,
is primarily limited to being rotated without substantial lateral
movements guided by the operator. Since the majority of files are
of the laminar type, this limitation poses a significant problem
Without the ability to laterally move the files, it is not possible
to make contact with every segment of the perimeter of the canal
and some portions may receive too much contact.
[0024] In any event, if the files are rotated passively in a
laminar canal or a canal which has a laminar-type anatomy for most
of its upper portion, the result is a circular opening whose
diameter corresponds to that of the file that was used. The file
typically stays in the center of the canal during rotation, such
that the tip of each file acts like a fulcrum and "ideally" stays
in the same position as a rotation point. Since each successive
file can move less laterally, each file simply makes a bigger
borehole than the preceding file. Accordingly, the files cannot
clean a root canal without significantly altering the original
anatomy by leaving a footprint or borehole corresponding to the
configuration of the instruments used. More specifically, the
result is a footprint or borehole with a perimeter that corresponds
to the perimeter of the biggest file that extends well beyond the
original anatomy of the root canal and yet in most instances does
not adequately clean significant portions of the root canal.
[0025] Although, the crown-down technique typically enables a
practitioner to more efficiently clean a root canal than the
step-back technique, they both require the practitioner to utilize
many different instruments. The need to frequently change the
cleaning instrument results in significant time requirements for
cleaning a root canal. However, careful instrumentation in
accordance with either tedious time consuming method does not avoid
the problems set forth above in relation to apical perforation,
wall perforation, overthinning or failure to clean all of the wall
surfaces.
[0026] Based on the foregoing observations, methods and systems are
needed in the endodontic arts which enable a dental practitioner to
remove and clean essentially all pulp material in a root canal
requiring root canal therapy.
[0027] It would also be an advancement in the endodontic arts to
provide methods and systems that are based on the three-dimensional
reality of teeth and do not relate solely to buccolingual x-ray
views, thereby enabling a practitioner to remove and clean pulp
material in a root canal without compromising the strength of the
walls and the apical anatomy.
[0028] It would also be a beneficial development in the endodontic
arts to provide methods and systems which encourage perimetrical
contact of the instruments with the canal walls.
[0029] Additionally, it would be an advancement in the endodontic
arts to provide methods and systems that enable a practitioner to
remove and clean pulp material in a root canal in a manner that is
less likely to result in failure due to bacterial contamination,
overly thinning the root canal, perforations or due to infected
material being pushed beyond the root from the coronal aspects of
canals.
[0030] Finally, it would also constitute progress in the endodontic
arts to provide methods and systems which yield a predictable
success rate, minimal risk of breaking an instrument, lower costs,
and an abbreviated operating time or an operating time that is at
least as efficient as conventional techniques.
SUMMARY AND OBJECTS OF THE INVENTION
[0031] An object of the present invention is to provide, methods
and systems which enable a dental practitioner to remove and clean
essentially all pulp material in a root canal requiring root canal
therapy by progressively cleaning sections of the root canal from
the crown to the apex.
[0032] Another object of the present invention is to provide
methods and systems developed based on the three-dimensional
reality of teeth and not just buccolingual x-ray views, thereby
enabling a practitioner to remove and clean pulp material in a root
canal without compromising the strength of the walls and the apical
anatomy.
[0033] An additional object of the present invention is to provide
methods and systems which encourage perimetrical contact of the
instruments with the canal walls.
[0034] Additionally, another object of the present invention is to
provide methods and systems that enable a practitioner to remove
and clean pulp material in a root canal in a manner that is less
likely to result in failure due to bacterial contamination, overly
thinning the root canal, perforations or due to infected material
being pushed beyond the root from the coronal aspects of
canals.
[0035] Finally, it is an object of the present invention to provide
methods and systems which yield a predictable success rate, minimal
risk of breaking an instrument, lower costs, and an abbreviated
operating time or an operating time that is at least as efficient
as conventional techniques.
[0036] Some of the features of the invention which enable these
objects to be achieved are as summarized hereinbelow after
explaining some unique terminology used in the application.
Applicant utilizes a terminology based on the methodology disclosed
herein. The term "operative root canal" refers to the pathway which
starts at the occlusal surface of the tooth, continues with the
cameral wall segment and the anatomical canal per se, and finally
reaches the foramen. Of course, the anatomical root canal extends
from the pulp chamber or the floor of the pulp chamber to the apex.
The operative root canal is divided into three sections or portions
which are referred to herein as "the operative coronal portion",
"the operative middle portion" and "the apical portion". The
operative coronal portion essentially includes the access cavity
walls. The operative middle portion is the upper portion of the
anatomical root canal while the apical portion is the lower portion
of the anatomical root canal. A typical apical portion is the last
or bottom 3 mm of the anatomical root canal.
[0037] The terms "operative coronal portion", "operative middle
portion" and "apical portion" are unique terms that are distinct
from the terminology conventionally utilized to refer to segments
of a root canal. In the conventional crown-down method, the canal
is customarily divided into the so-called "three thirds",
including: the crown, the middle third, and the apical third. In
reference to the conventional crown-down method, it is common to
use the term "coronal third" to refer to the first part of the
"anatomical" canal, originating at the floor of the pulp chamber or
the upper limit of the middle third into which a tooth is
customarily divided, with a theoretical line at the height of the
neck.
[0038] During the root canal therapy, the pulp chamber can be
opened to expose the anatomical root canal by any conventional
method or instrument. Additionally, conventional methods and
instruments can be used to prepare the operative coronal portion.
However, unique methods and instruments are used in the operative
middle portion while preferably simultaneously abrading the
operative coronal portion. Additionally, after the operative middle
portion has been cleaned, unique methods and instruments are used
to improve access into the apical portion and to then clean the
apical portion.
[0039] By envisioning the root canal as starting at the occlusal
surface, practitioners can immediately identify any "interferences"
or obstructions, as well as any protrusions of enamel, which may be
disregarded. As a result, the instruments disclosed herein come
into contact with every segment of the canal walls, including the
obstructions, in order to achieve anatomical widening and also the
rectification or straightening of the first two portions of the
canal which include the operative coronal portion and the operative
middle portion. This procedure opens the pathway for the
preparation of the apical portion of the canal. The term
"interference" refers to everything in the operative canal that
hinders the rectilinear insertion of the instruments used, during
the final cleaning phase of the procedure, preparation of the
apical portion. The term "rectification" refers to the placement of
the operative coronal portion or access cavity on the same axis as
the operative middle portion. Rectification is achieved through the
removal of interferences from the operative coronal portion and
preferably from the operative middle portion of the operative canal
as well.
[0040] The methodology disclosed herein involves the use of
distinct instruments in the three portions of the anatomical root
canal in different phases such that the root canal is cleaned
progressively and sectionally. The instrument(s) associated with
each phase have been designed specifically for that particular
phase and accordingly have unique customized characteristics and
features.
[0041] By cleaning the root canal in sections, the instruments can
be adapted to the perimetrical or perimetral anatomy of the root
canal. As a result, the entire perimeter or substantially all of
the perimeter is contacted and cleaned along the length of the
perimeter without substantially altering the configuration of the
perimetrical anatomy. For example, a perimetrical anatomy that was
primarily tubular or laminar will be enlarged but will still be
primarily tubular or laminar. There will not be a large round
borehole in the canal superimposed on the original perimetrical
anatomy which corresponds to the diameter of the file that is used;
as is the case with the nickel/titanium files used in crown down
procedures that stay in the center of the canal even when the canal
is laminar.
[0042] Additionally, the invention also enables the practitioner to
prepare root canals in accordance with the anatomy of the root
canal, even though the practitioner may not have been able to
adequately identify the overall anatomy due to the inability to see
the root canal as is the case from the mesial-distal view using
standard radiography. Further, the invention also enables the
practitioner to adapt to the contours of the root canal of all
different types of teeth, by guiding instruments that have been
designed to come into contact with every perimetrical segment of
the walls.
[0043] Once the pulp chamber has been opened to expose the
anatomical root canal, then the operative middle portion can be
accessed. Before accessing the operative middle portion, however,
it is necessary to determine the so-called "working length" of the
first two portions of the operative root canal including the
operative middle portion and the operative coronal portion. The
methods for identifying the working length involve the use of
x-rays or videography, performed with the aid of a centering device
and through use of the long-cone method After the working length
has been determined, then the proper instruments can be selected
for use in the preparation of the operative middle portion.
[0044] The working length is determined by measuring the canal axis
from the occlusal plane, in order to arrive at the apical limit of
the root as indicated on the x-ray. A distance of 3 mm is deducted
from the measured length. The result is the maximum working depth
that the operative middle portion instrument(s) should reach. The
foregoing calculations also figure in the predetermination of the
working lengths for all other instruments utilized in the
procedure. The instruments preferably are selected to have files
with lengths that are equal to the working length; however, stops
may also be used to ensure that the files have the desired working
length.
[0045] In addition to the anatomical widening of the perimeter of
the operative middle portion, the preparation of the first two
portions also involves the removal of the interferences from the
operative coronal portion and the operative middle portions,
thereby allowing the rectification of the first two portions of the
operative root canal. Please note that during preparation of the
operative middle portion and rectification of the first two
portions, any and all intrusion of the instrument(s) into the
apical portion is avoided. The boundary between the operative
middle portion and the apical portion has been estimated to be
located between 3 mm and 5 mm from the end of the root canal, as
shown on the x-ray. After preparation of the operative middle
portion and rectification of the first two portions have been
completed, the procedure moves to the third stage, in which the
apical portion is prepared.
[0046] After the working length has been determined for the first
two portions including the operative coronal portion and the
operative middle portion, the operator selects an instrument from a
set of instruments designed for use in the operative middle
portion. Each instrument in the set of instruments comprises a
handle connected to a file with an abrasive surface or in other
words a shaft with tines or an abrading portion. Each file in the
set has the same length which is selected such that the operative
middle portion of the operative root canal is cleaned without
significantly removing pulp material from the apical root portion.
Additionally, each file is designed to have a taper that is larger
than the taper of each preceding file. Each file or shaft has an
abrading portion for abrading the surfaces or walls of the root
canal. In contrast to conventional files, as set forth in greater
detail hereinbelow, the abrading portion may extend along the
entire length of the file to enable the instrument to be used to
clean the operative middle portion while also abrading the
operative coronal portion.
[0047] The files of the instruments in the first set are preferably
formed from stainless steel to enable the file to be moved in the
desired manner. The files of the instruments in the first set are
designed such that each file has sufficient flexibility to be
flexed or curved to urge the abrading portion against the surfaces
of the root canal and sufficient rigidity to apply pressure against
the surfaces of the root canal as the abrading portion of the file
is urged against the surfaces of the root canal and simultaneously
moved in a cleaning motion. Additionally, the files have adequate
resilience to avoid being substantially deformed as the file is
flexed or curved to urge the file, particularly the abrading
portion, against the surfaces of the root canal.
[0048] The contours of the perimeter of the root canal in the
operative middle portion are followed as the file of the
instrument(s) is flexed or curved against the surfaces of the root
canal and simultaneously moved in a cleaning motion. Since the
contours are followed, the perimeter is widened and smoothed but
the original shape is not substantially altered.
[0049] After the operative middle portion has been cleaned, the
apical portion may be cleaned by several different techniques or
combinations thereof. One method involves no abrasive
instrumentation within the apical portion just insertion of
appropriate irrigation instruments. Since removal of the pulp
material from the operative middle portion removes the majority of
bacteria in the pulp canal, it has been found that it may not be
necessary to abrade the apical portion.
[0050] Irrigants are delivered into the apical portion to maintain
the debris derived from cleaning the root canal in suspension. The
debris is then removed as the particles of the smear layer yielded
from the action of the files used to prepare the canal may result
in clogging the apical portion of the root canal with a plug. After
the debris has been removed, the proper preparation and filling of
the apical portion of the root canal can be achieved.
[0051] By eliminating or minimizing abrasive instrumentation within
the apical portion, the potential for complications is diminished.
As discussed above in the Background, most errors in performing
root canals occur during instrumentation of the apical portion of
the root canal. The apical portion is the most delicate part of the
root canal and it is the most distally located Accordingly, it is
highly advantageous to just irrigate and then remove the irrigant
and debris, since many complications occur during abrasive
instrumentation.
[0052] However, in some instances, it may be necessary to improve
access into the apical portion such that an irrigation needle can
be deployed to deliver irrigants to the apical portion. Access into
the apical portion is improved by widening, for example, at least
the entrance of the apical portion or the entire apical
portion.
[0053] Alternatively, another method involves the use of a set of
instruments designed for cleaning the apical portion in an abrasive
manner. Such a method may be initiated directly after the operative
middle portion of the operative root canal has been cleaned.
However, it may be necessary to have two phases of instrumentation
within the apical portion of the operative root canal including
widening and abrasive cleaning of the apical portion. More
particularly, it may be necessary to improve the access into the
apical portion before performing the abrasive instrumentation by
widening the transition between the operative middle portion and
the apical portion to enable irrigants to be delivered into the
apical portion.
[0054] These and other objects and features of the present
invention will become more fully apparent from the following
description and appended claims, or may be learned by the practice
of the invention as set forth hereinafter.
BRIEF DESCRIPTION OF THE DRAWINGS
[0055] In order that the manner in which the above-recited and
other advantages and objects of the invention are obtained, a more
particular description of the invention briefly described above
will be rendered by reference to a specific embodiment thereof
which is illustrated in the appended drawings. Understanding that
these drawings depict only a typical embodiment of the invention
and are not therefore to be considered to be limiting of its scope,
the invention will be described and explained with additional
specificity and detail through the use of the accompanying drawings
listed hereinbelow.
[0056] FIG. 1 is a view of a system of endodontic tools including a
first set of instruments for cleaning the operative middle portion
of an operative root canal, a second set of instruments for
improving the access into the apical root portion and a third set
of instruments for cleaning the apical root portion.
[0057] FIGS. 2A-2B show embodiments of endodontic files operated by
a driver, such as an electric motor or an air turbine, with lengths
that enable the portions of the root canal above the apical portion
to be cleaned.
[0058] FIG. 2C is an enlarged transverse cross-sectional view of
the tooth shown in FIG. 2A taken along cutting line 2C-2C to show
that the anatomy of the root canal has not been substantially
altered by the cleaning thereof and to show the shaping of the
canal in preparation of filling the root canal.
[0059] FIG. 3 is a longitudinal cross-sectional view of a tooth
with a file inserted into a root canal having a length that is
sufficient to reach the apex.
[0060] FIG. 4 is a perspective view of another embodiment of a set
of endodontic instruments for cleaning of the coronal portion and
operative middle portion of a root canal.
[0061] FIG. 5A is a depiction of a practitioner employing an
endodontic irrigation tip to demonstrate the convenience of
employing the angled tip.
[0062] FIG. 5B is a view of a cross section of a tooth with the
apical root portion being irrigated by the endodontic irrigation
tip shown in FIG. 5A.
[0063] FIG. 6A is a cross-sectional view of a tooth after the pulp
chamber has been accessed and before rectification.
[0064] FIG. 6A is a cross-sectional view of a tooth after the pulp
chamber has been accessed and before rectification.
[0065] FIG. 6B is a cross-sectional view of the tooth shown in FIG.
6A after rectification and after the operative middle portion has
been cleaned.
[0066] FIG. 6C is a cross-sectional view of the tooth shown in FIG.
6A after the apical portion has been widened.
[0067] FIG. 6D is a cross-sectional view of the tooth shown in FIG.
6A after the apical portion has been cleaned.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
[0068] The present invention relates to systems and methods for
cleaning root canals through the removal of pulp material from the
root canals. The invention provides for cleaning the root canal in
progressive sections from crown to apex. FIG. 1 depicts a system of
instruments that includes three distinct sets. After the pulp
chamber is opened and preferably after further preparations,
instruments from a first set of instruments such as set 10 are
sequentially introduced into the root canal to clean the root canal
up to the apical root portion or in some instances a single
instrument is used. The apical portion is preferably cleaned by
delivering an irrigant into the apical portion and then removing
the irrigant along with any debris. In some instances, an
additional instrument or set of instruments may be optionally
introduced to improve the access into the apical portion for
introduction of a cannula of an irrigation tip such as set 40.
Alternatively, the apical root portion may also be cleaned with
another instrument or set of instruments such as set 70.
[0069] The invention enables a dental practitioner to remove and
clean essentially all the pulp material in a root canal requiring
root canal therapy. The cleaning is achieved in a manner that is
safer in terms of over thinning of the root canal and perforations
and yet requires less instrumentation than conventional
techniques.
[0070] To appreciate the nomenclature used for these sets,
reference is made to FIGS. 2A-2B and 3 which depict a molar 240 in
various stages of the root canal cleaning procedure. The sections
of the operative root canal being cleaned in FIGS. 2A-2B include
the operative coronal portion 260 and the operative middle portion
262. The remainder of the operative root canal, the apical portion
264 is shown being cleaned in FIG. 3. The operative coronal portion
260 essentially includes the access cavity walls down to the floor
256 of pulp chamber 246. The operative middle portion 262 is the
upper portion of the anatomical root canal while the apical portion
263 is the lower portion of the anatomical root canal. A typical
apical portion 264 is the last or bottom 3 mm or 4 mm of the
anatomical root canal. Stated otherwise, the apical portion of the
root canals shown in FIGS. 2A-3 is the 3 mm to 4 mm above apices
254a and 254b. However, the actual length of the apical portion
varies depending on many factors such as the type of tooth and the
age of the tooth.
[0071] The divisions of the operative root canal are distinguished
from the nomenclature of the anatomical root canal as used to
designate the sections before opening the tooth wherein the
anatomical root canal is divided into the apical portion and the
coronal portion. The coronal portion of the anatomical root portion
is conventionally defined as the upper portion of the anatomical
root canal which terminates at the floor of the pulp chamber.
However, once the pulp chamber is exposed and instruments are
introduced into the root canal, the opening into the tooth should
be treated as an extension of the operative root canal as it is
then a continuous chamber or open tract. Accordingly, the access
walls are considered part of the operative root canal and are
designated as the operative coronal portion 260. In reference to
the anatomical root canal 252a, the operative middle portion 262 is
defined as extending from floor 256 down to an area of anatomical
root canal 252a, such that the length of the operative middle
portion is the top two-thirds of anatomical root canal 252a.
[0072] As previously indicated, the three sections are treated in
primarily distinct sequential phases including: preparation of the
operative coronal portion, then cleaning or preparation of the
operative middle portion, optionally improving access to the apical
root portion and finally cleaning of the apical portion preferably
by just irrigating the apical portion or alternatively by use of
abrasive instrumentation.
[0073] Before the sets of instruments in the system shown in FIG. 1
are utilized, it is first necessary to expose the pulp chamber by
removing the top of the chamber. This can be achieved, for example,
through the use of an instrument such as an instrument with a bur,
which is preferably a diamond bur used in conjunction with a low or
high speed handpiece. However, any suitable instrument can be
utilized such as those disclosed in Italian Patent No. 1,142,983 or
Italian Patent No. 1,149,157, which are hereby incorporated by
reference. This first phase in the procedure also preferably
involves other steps to enhance accessibility into operative middle
portion 262 and also apical portion 264.
[0074] After the pulp chamber has been exposed during the first
phase, it is preferable to remove or reduce dentinal or enamel
protrusion or irregularities that may obscure or hinder access of
instruments into the remaining portions of the operative root canal
during the subsequent phases. FIG. 2A shows a dentinal shelf 266
above root canal 252b while the overhanging portions of enamel 242
and dentin 244 have been removed on the other side above root canal
252a in preparation for removing pulp material 250 from root canal
252a. Interferences are preferably removed or minimized such that
instruments can be inserted in the anatomical root canal in a
relatively straight manner. Rectification or regularization can be
achieved by any suitable means. An example of a means for
rectifying dentinal shelves is set forth in U.S. Pat. No. 5,642,998
and in U.S. Pat. No. 5,775,904 which were incorporated by reference
hereinabove. It may also be necessary to widen the tract of the
operative coronal root canal. Some dentists may prefer to obtain
greater access through a cuspidectomy. Note that during the root
canal procedure, a rubber dam is typically used to isolate the
tooth, which may require in some instances, the rebuilding of the
pulp chamber walls. During this phase as well as the others, it is
generally necessary to irrigate the root is canal with irrigants or
a root canal conditioner/lubricant.
[0075] Once the operative coronal portion has been properly
prepared, then the three sets of instruments shown in FIG. 1 can be
used. These three distinct set of instruments are each specifically
referred to as: a set of instruments for cleaning the operative
middle portion, identified as operative middle portion set 10; an
optional set of instruments used to improve access into the apical
root portion, identified as optional set 40; and a set of
instruments for removing and cleaning essentially all pulp material
from the apical root portion, identified as apical portion set 70.
File 14a of instrument 10a from operative middle portion set 10 is
shown being used in FIGS. 2A-2B to clean to clean the pulp material
250 from the root canal operative middle portion 262 of root canal
252a. Once operative middle portion 262 has been cleaned, then the
apical portion 264 is cleaned as shown in FIG. 3 with one of the
instruments from apical portion set 70 such as 70d. In some
instances, it is necessary to use an instrument from optional set
40 before cleaning the apical portion in order to widen the
transition from the operative middle portion 262 to apical portion
264.
[0076] The sequential use of each set and features of the
instruments are discussed below, specific details of an exemplary
embodiment of a system of sets is provided below in detail in
Example 1 of the Examples of the Preferred Embodiment. It should be
understood, however, that each instrument has a file with a top end
extending from a handle. File instruments can also be manufactured
that are just a file without a handle.
[0077] After the operative coronal portion has been adequately
prepared, the overall length of the root canal is identified,
typically by use of radiography, in order to determine the
preferred working length for the instrument or set of instruments
to be used. Once the overall length of the root canal has been
identified, then the combined length of operative middle portion
262 and the operative coronal portion 260 are determined by
subtracting about 3 mm to about 4 mm from the overall length.
Determination of the combined length of operative middle portion
262 and the operative coronal portion 260 enables the practitioner
to select a set such as set 10 with instruments having files with
lengths that are appropriate for cleaning or preparation of
operative middle portion 262. The total radiographic length is
preferably derived from a radiograph made using a localizator and a
long cone radiographic head.
[0078] Once an instrument or a set of instruments have been
selected that have an appropriate length then the next phase in the
procedure can proceed as shown in FIG. 2A. While the primary
objective in this phase is cleaning or preparation of operative
middle portion 262, it may also involve to some extent further
rectification of the operative coronal or access portion 260
through further removal of any ledges or outcroppings which prevent
straight and easy access into the operative middle portion 262.
Additionally, it may also involve some degree of rectification of
the upper region or segment of operative middle portion 262.
[0079] As shown in FIG. 2A, a file such as file 14a of file
instrument 10a is inserted into root canal 252, down through
operative middle portion 262 without extending substantially into
apical portion 264. After file instrument 10a is used, then the
other three instruments 10b-d are sequentially used to further
clean and shape operative middle portion 262 and operative coronal
portion 260.
[0080] File instrument 10a has a file 14a extending from handle
12a. File 14a has a shank portion 16a and tines or an abrading
portion 19a. The abrading portion extends from tip 18a to shank
portion 16a at the top end of file 14a. The features of the other
files are similarly numbered.
[0081] By properly selecting a combination of factors including the
diameters of the files at the top ends and at the tips as well as
the material used to form the files, the files are designed such
that each file has sufficient flexibility to be flexed or curved to
urge the abrading portion against the surfaces or walls of the root
canal and sufficient rigidity to apply pressure against the
surfaces of the root canal as the abrading portion of the file is
urged against the surfaces of the root canal and simultaneously
moved in a cleaning motion. Additionally, the files have adequate
resilience to avoid being substantially deformed as the file
instrument is flexed or curved to urge the abrading portion against
the surfaces of the root canal.
[0082] As shown in FIG. 1, the diameter of the top end of each
abrading portion is incrementally larger when comparing files
14a-d. Accordingly, the diameter of the top end of each successive
file introduced into the operative middle portion is greater than
the diameter of the top end of each preceding file.
[0083] The diameter of each tip 18 in a set of instruments is
essentially the same such that the diameter of tip 18a is about the
same as the diameter of tips 18b-d. For example, a set of
instruments may all have tip diameters of about 0.10 mm. A set may
also be designed such that the instrument intended to be inserted
first has a tip diameter of about 0.10 mm while the other
instruments in the set have a tip diameter of about 0.13 mm. A set
with slightly different tip diameters, such as a set of three or
four instruments with respective tip diameters of 0.10 mm, 0.10 mm,
0.13 mm and 0.13 mm, and in any event not exceeding 0.15 mm, is
still considered to have substantially constant tip diameters
within the set as the difference in size is very minor and the
diameters do not sequentially increase for each instrument. In an
alternative embodiment, the tip diameter may vary between
instruments in a set such that, for example, the tip diameter of
each sequentially inserted file is progressively larger. The tip
may be generally sharp and configured for at least minimal cutting
capability. The tip may also be more rounded such that the tip has
essentially no cutting capability.
[0084] Since the tip diameters are essentially equal and since the
diameter of the top end of each successive file introduced into the
operative middle portion is larger than the diameter of the top end
of the preceding file, the taper of the abrading portion of each
successive file in the set is larger than the abrading portion of
the preceding file. For example, the taper may range from 0.02 to
0.13 and increase in increments for each successive file. Each
successive file accordingly has an increased surface area for
cleaning the root canal. Additionally, as files are inserted into a
root canal with larger and larger tapers, the rigidity of the upper
half of each successive file also increases or more particularly,
the rigidity of the upper half of each successive abrading portion
increases. The increase in rigidity in the upper half enables the
practitioner to more easily remove interferences and to properly
rectify the operative coronal portion 260 and the operative middle
portion 262. The sequential use of files in a set wherein each file
has greater rigidity than the previously introduced file along at
least an upper part of the abrading portion of each file enables
each sequentially introduced file to more rapidly and aggressively
clean than the previously introduced file. The cleaning is more
rapid and aggressive as at least the top end of each abrading
portion of each sequentially introduced file applies greater force
against the root canal surfaces than the previously introduced
file. Accordingly, the contours can be gently followed by the
instrument or instruments initially used and then the contours of
the root canal can be followed by the subsequently used instruments
as the root canal is more aggressively shaped. Note that the
rigidity does not increase in a manner that prevents even the final
instrument used in the cleaning of the operative middle portion and
the operative coronal portion from following the contours of the
root canal.
[0085] When the tip diameter remains essentially the same for the
instruments in the set and the taper is increasingly larger for the
abrading portion of each sequentially used instrument the top end
of each abrading portion is more rigid for each sequentially used
instrument, however, the rigidity at the tip is about the same.
Stated otherwise, the difference in rigidity between the abrading
portions of the files diminishes from the top end of each abrading
portion to the tip. While there may be some comparative increase in
rigidity at the lower region of each sequentially utilized abrading
portion, the increase in rigidity is not as pronounced or is
sufficiently nominal to have little effect when compared with the
increase at the top end of each abrading portion. Note that the
flexibility of the lower portion, particularly within the region
closest to the tip, also remains essentially constant. In other
embodiments, the taper of the abrading portions may be constant and
have increasing rigidity along the entire length when compared to
the previously inserted file by designing the files with larger top
ends and larger tip diameters.
[0086] The consistency in rigidity and flexibility at the lower
region or half is useful since the lateral perimetrical force
applied to the handle is primarily transferred to its upper half or
at least the part closest to the handle, which is the strongest
part of the file. So as the upper part of the abrading portion is
aggressively urged against root canal surfaces, the force applied
by the lower part of the abrading portion is not significantly
different. This is beneficial since root canals taper in diameter.
Additionally, a root canal that is laminar at the top of an
operative middle portion often tapers to a configuration that is
primarily round. In such instances, the tip of the file rotates in
a round root canal segment while the top end of the abrading
portion is pushed around the laminar perimeter of the top of the
operative middle portion The file can be formed from any suitable
material. In forming a file, the material is preferably selected in
view of the dimensions and design, to yield a file having the
desired properties with respect to flexibility, resilience and/or
rigidity as set forth above. The preferred material for forming
files used to clean the operative middle portion of root canals is
stainless steel. Other metals can also be used such as
nickel/titanium; however, it may be necessary to design the files
to have larger diameters than files formed from stainless steel
when using nickel/titanium as nickel/titanium tends to be more
flexible than steel. Alternatively, the files can be formed from
suitable non-metal materials, such as a plastic.
[0087] When the files are formed from stainless steel or a material
with comparable properties, the top end diameter of each file,
where the abrading portion terminates, may range from about 0.25 mm
to about 2 mm. However, the diameter will more typically range from
about 0.4 mm to about 1.7 mm and most typically from about 0.5 mm
to about 1.6 mm. Additionally, when the files are formed from
stainless steel or a material with comparable properties, the tip
diameter of each file may range from about 0.06 mm to about 0.4 mm.
More typically, however, the tip diameter will range from about
0.08 mm to about 0.15 mm and most typically from about 0.10 mm to
about 0.13 mm.
[0088] The length of each file in the set used to clean the
operative middle portion depends on the length of the tooth being
cleaned. As discussed above, after identifying the length of the
root canal from an x-ray image, the length of the file to be used
in the operative middle portion is determined by subtracting at
least 3 mm from this identified length of the root canal. To
accommodate the various root canal lengths which may be
encountered, it is preferred to have files with lengths ranging
from about 8 mm to about 35 mm. However, files with lengths ranging
from about 10 mm to about 30 mm are most frequently utilized and
files with lengths ranging from about 18 mm to about 30 mm are the
most frequently utilized.
[0089] As discussed above, each file 14a-d of each file instrument
10a-d in set 10 has a length that is only sufficient to enable the
file to contact the operative middle portion and the operative
coronal portion of the root canal. The file length of files 14a-b
enables a practitioner to aggressively clean the operative middle
portion without worrying that the instrument will overly thin the
root canal, perforate the apex or that cleaning will cause
extrusion of material through the apex. Another benefit of cleaning
the operative middle portion 262 first is that the apical portion
264 is then generally more accessible and easily cleaned.
Additionally, since instruments are selected for use in cleaning
the operative middle portion 262 which have files lengths that do
not permit entry into the apical portion 264, the likelihood of
jamming or breaking a tip of an instrument while working in the
confined space of the apical portion 262 is prevented.
[0090] By instrumenting in the operative middle portion 262 and the
operative coronal portion 260 before cleaning the apical portion,
the practitioner can use an instrument that is relatively flexible
compared to the conventional instruments. As shown in FIG. 2B,
which is a cross-sectional view taken along cutting line 2B-2B of
tooth 240 in FIG. 2A, file 14a of file instrument 10a is
sufficiently flexible to be flexed against any surface of operative
middle portion 262 or operative coronal portion 260 and yet is
sufficiently rigid to remain flexed against the surface during a
cleaning motion such as a longitudinal motion, a rotational motion
or a reciprocating rotational motion.
[0091] File instrument 10a is shown in FIGS. 2A-2B being moved in a
longitudinal movement or up and down movement as well as being
rotated while file 14a is flexed or arched to urge the file against
the root canal surfaces. As shown, the configuration and mechanical
properties of the files used to clean the operative middle portion
262, and preferably the operative coronal portion as well 260,
enable a practitioner to move the files around the perimeter or
from side to side to contact the perimeter. Such movements enable
the file to follow the contours of the root canal. Further, since
the file is moved around the perimeter, the file has more than one
center of motion during cleaning of the operative middle portion of
the root canal, such as a pivot point or center of rotation, as the
tip of the file or at least a part of the abrading portion does not
generally remain primarily in one position.
[0092] In addition to cleaning a root canal, the instruments also
simultaneously shape the root canal for subsequent filling with a
filling material such as gutta percha. Cleaning and shaping a root
canal generally necessitates the widening of portions of the pulp
canal and smoothing some contours of the pulp canal to yield a
wider and smoother canal. The amount of dentin removed during the
cleaning and shaping is preferably no more than just sufficient to
adequately shape the root canal for subsequent filling.
[0093] Once the cleaning and shaping of root canal 252a is
completed, it appears as shown in FIG. 2C. FIG. 2C is a transverse
cross-sectional view of root canal 252a taken along cutting line
2C-2C in FIG. 2A through cementum 248 and dentin 244. In addition
to depicting the configuration of the cleaned and shaped root canal
after file 14a has been removed, FIG. 2C also shows in phantom
lines the original configuration of the perimeter of the pulp canal
252a. Note that shaped walls 268a generally have the same laminar
shape as did the walls of pulp canal 252a before being cleaned and
shaped.
[0094] Due mainly to the configuration and mechanical properties of
the files, the contours of the operative coronal portion and the
operative middle portion can be used during the cleaning by a
practitioner as a guide for the movements of the files as the files
are pushed against the surfaces of the root canal and
simultaneously moved around the perimeter or periphery of the root
canal until the practitioner has reached the beginning location of
the cleaning and shaping process. By adapting to the perimetrical
or perimetral anatomy of the root canal, the entire perimeter or
substantially all of the perimeter is contacted and cleaned along
the length of the perimeter without significantly altering the
configuration of the perimetrical anatomy such that the original
anatomy of the root canal or shape of the perimeter is essentially
maintained. For example, in root canals that are laminar such as
the cross-sectional shape of pulp canal 252a shown in phantom lines
in FIG. 2C, the files can be urged along one side and then along
the next side wall in a manner such that the resulting cleaned and
shaped root canal is generally widened but has a perimeter that is
still generally laminar such as shaped walls 268a as shown in FIG.
2C. Similarly, if the original shape of the perimeter of a root
canal as seen from a transverse cross-sectional view is generally
circular or tear shaped, then the cleaned and shaped walls will
also be generally circular or tear shaped. In other words, the
original anatomy of the root-canal controls the shape of the
resulting cleaned and shaped anatomy due to the cleaning techniques
enabled by the present invention.
[0095] Since a perimetrical anatomy that was primarily tubular or
laminar will be enlarged but will still be primarily tubular or
laminar, the tooth is less likely to be weakened as compared with
prior art methodologies. As discussed above, prior art methods
yield a final anatomy that is dictated by the shape of the
instrument and result in the formation of a borehole in the root
canal that obviously corresponds to the shape of the file. Forming
a significant footprint in a root canal from the use of instruments
in accordance with prior art methodologies not only weakens a
tooth, it also increases the risk that the tooth can be overly
thinned or that perforations may result. Additionally, such prior
art methods fail to fully clean the root canal since significant
portions of the perimeter are not even contacted by the instruments
along the length of the root canal.
[0096] Cleaning the root canal, particularly the operative middle
portion, without substantially altering the anatomy of the root
canal results in a lesser likelihood of overly thinning the root
canal or causing lateral perforations as compared with prior art
methods. The likelihood of such complications occurring during
instrumentation of the operative middle portion is further
diminished since the instrument does not extend into the apical
portion. This understanding enables a practitioner to more
confidently urge a file such as file 14a against all surfaces of
root canal 252 and aggressively clean all of the surfaces of
operative middle portion of the root canal.
[0097] Another advantage of the configuration and mechanical
properties of operative middle portion instruments, such as file
14a shown in FIGS. 2A-2B, is that the file can simultaneously
abrade both operative coronal portion 260 and operative middle
portion 262. The files can simultaneously abrade both portions as
each file has an abrading portion along their entire length or
along substantially all of their length. A primary benefit of
simultaneously abrading both portions is the ability to farther
straighten the operative coronal portion 260 while cleaning the
operative middle portion 262.
[0098] Use of files in the operative middle portion which have an
abrading portion along their entire length or along substantially
all of their length such as abrading portions 19a-d is in contrast
to files formed in accordance with ISO standardization. ISO
standardized files have abrading portions of up to 16 mm and the
remainder of the file is a smooth shank. Since such files are
inserted down to the apex, it is generally not possible to abrade
any portion beyond the anatomical root canal. Additionally, since
such ISO standardized files frequently fail to remove interferences
extending from the access or root chamber above the anatomical root
canal, the instrument must bend around the interferences, thereby
further increasing the likelihood of wall perforations,
overthinning and failing to clean significant portions of the
canal. Use of such conventional instruments especially increases
the likelihood of iatrogenic modifications resulting from the tip
of the file.
[0099] The abrading portions 19a-d extend along most of the length
of each file 14a-d. As shown in reference to FIG. 4, files
14a'-14c' may also be provided with abrading portions 19a'-19c'
that extends along their entire lengths. The advantage of files
having a shank portion such as shank portions 16a-d include the
ability to easily utilize stops or to include incremental markings
on the shank portion. In an embodiment that utilizes no stops such
as the files shown in FIG. 4, the length of the file and the
abrading portion are the same.
[0100] The abrading portion is at least the outer edge of the file.
The abrading portion of the files in FIGS. 1 and 4 are formed by
twisting a blank such as a rectangular blank. Conventional
techniques such as twisting, cutting and appropriately machining a
precursor blank to form abrading portions such as cutting surfaces
or helical features with the appropriate screw periodicity can be
utilized alone or in combination. The abrading portion can also be
formed by cutting lands in a precursor blank having three or four
sides or a cylindrical rod. A precursor blank or rod may also be
abraded to impart a roughened surface. Additionally, the file may
have an abrading portion that is a knurled surface. Any
conventional methodology may be used to form the abrading portion
and the file may have an abrading portion that appears like
conventional K-files or Hedstrom-type files.
[0101] While the files may have any suitable transverse
cross-sectional shape, they are preferably configured in a manner
such that the potential for breakage is minimized. For example, a
file with a square cross-section may be preferred over a triangular
cross-section as the file with a square cross-section has a greater
mass and is accordingly less likely to break. Additionally, a file
configured with tines or extensions having wide angles are
generally preferred over those with narrow angles. However, the
preferred tine configuration depends primarily on the particular
use as in some instances it is desirable to aggressively cut while
in others the root can be more passively cut. When it is more
desirable to aggressively cut, it may be preferred for example to
utilize a file with relatively narrow tines. As indicated above,
the abrading portion may also include abrasive particles positioned
on the file. One or more instruments in a set may have a file with
abrasive particles while the others may have abrading portions
formed by other techniques. Additionally, only a part of the file
may have abrasive particles such as the upper section for more
aggressive shaping or rectification of the root canal. The abrasive
particles are preferably diamonds. The application, impregnating,
coating or attachment of the abrasive coating may be achieved by
any conventional method. All of the files in combination with their
respective abrading portions disclosed herein are examples of means
for removing and cleaning of pulp material as the file instrument
is operatively moved. Additionally, each abrading portion disclosed
herein is an example of a means for abrading a root canal.
[0102] File instrument 10a is preferably used in conjunction with
an endodontic handpiece designed for movement of endodontic file
instruments as shown in FIGS. 2A-2B at 100. The endodontic
handpiece 100 and file 10a are drawn in phantom lines to represent
the ability of the file to be moved and flexed as root canal 252a
is cleaned. File instrument 10a can be continuously rotated in one
direction only or file instrument 10a can be rotated in a
reciprocating motion such that file instrument 10a rotates for
example, clockwise for half of a revolution and then
counterclockwise for half a revolution. A reciprocating motion is
preferred as such motion enables the file to alternately engage
material 250 and the walls of the operative middle portion of the
root canal in a manner that removes material 250 and to then rotate
in the opposite direction such that the file less aggressively
engages material 250 and the operative middle portion walls,
depending on the file design. Accordingly, rotating file instrument
10a in a reciprocating motion minimizes breakage of file 14a when
file 14a encounters a surface that prevents rotation of file
instrument 10a in a direction that enables cleaning and removal of
material 250. File instrument 10a can also be vibrated or
manipulated by hand. Hand milling is, however, more difficult and
time consuming.
[0103] The optional stop 140 shown being utilized is generally not
necessary since the file length can be selected to correspond
closely with the combined length of the operative coronal portion
and the operative middle portion. Stops such as stop 140 may be
used to ensure that the length of the portion of the file inserted
into the tooth is such that the file does not extend significantly
into the apical root portion. The advantage of using such a stop is
that less sets of instruments are needed in order to have a set
that can be utilized in teeth of varying lengths. Accordingly,
files 10a-d have shank portions 16a-d that are preferably in a
range from about 2 to about 4 mm in length and that are more
preferably about 3 mm long to enable stops to be positioned as
needed. Note that while a stop is shown with a thickness of about 1
mm, stops may have varying thickness. Also, the stops may also be
positioned such that one or more stops are positioned adjacent to
the handle such that movement is not possible since the stops
already abut the handle. All of the stops disclosed herein are
examples of stop means for limiting the operative middle portion
instrument means to insertion into the operative coronal portion
and the operative middle portion.
[0104] When a stop is used, the length of the root canal from an
x-ray image is first identified and then the length of the root
canal above the apical root portion is determined by subtracting 3
mm from this identified length of the root canal. An instrument is
then selected that has a length that is slightly longer than the
determined length of the root canal down to the apical portion.
Note that this determined length is the combined length of the
coronal portion and the operative middle portion.
[0105] It may also be advantageous to use a stop such as stop 140
to more easily flex the file against the root canal surfaces. More
particularly, using an instrument with a stop alters the curvature
of the file since the portion above the stop is also flexed. This
results in a different flexed configuration or pivot point so that
greatest pressure is applied at a higher part of the root canal
than when an instrument is used without stops. The desirability of
applying pressure in such a manner depends on the particular tooth.
Note however that if an instrument is used without a stop then the
portion of the file that is flexed against the root canal can also
be used to abrade sections thereabove by merely moving the file
upward as it is flexed. Whether a stop is used or not, the file can
always be moved further above the apical portion so that it is
easier to arch the file. For example, FIG. 2B shows tip 18a of file
14a nearly reaching the apical portion 264 and also shows file 14a
in phantom after being moved higher in root canal 252a and being
more significantly arched.
[0106] It is also possible to utilize the file instruments with a
unique handpiece such as is disclosed in U.S. patent application
Ser. No. 09/639,699 entitled Endodontic Instruments Adapted to
Provide Variable Working Lengths and Related Methods for Using the
Instruments which was filed on Aug. 16, 2000 by Francesco Riitano
and Dan E. Fischer and is owned by Ultradent Products, Inc. Ser.
No. 09/639,699 was filed as a continuation-in-part application of
U.S. patent application Ser. No. 09/425,849 entitled Incrementally
Adjustable Endodontic Instruments which was filed on Oct. 22, 1999
by Dan E. Fischer and is owned by Ultradent Products, Inc. Ser. No.
09/639,699 and Ser. No. 09/425,849 are hereby incorporated by
reference. The handpiece 100 shown in FIGS. 2A-2B corresponds with
the handpieces disclosed in Ser. No. 09/639,699 and Ser. No.
09/425,849. One of the advantages of handpiece 100 is that all of
its bottom surfaces are essentially coplanar so that its rim may be
used as a stop as it is rested on the coronal surface of tooth 240.
The ability to use the rim as a stop eliminates the need for rubber
stoppers. Although, it is not necessary to use a stop when using
instruments adapted for use with handpieces as disclosed in the
above-identified applications, a stop is shown being used in FIGS.
2A-2B in order to illustrate the use of stops with handpieces in
general. Another advantage of handpiece 100 is that the position of
handle 12a may be adjusted relative to the chuck as the chuck
applies mechanical pressure against handle 12a to hold handle 12a
within the chuck. Chuck 100 enables handles to be held whether they
have a latch such as the latch-type handles 12a'-c' designed for
coupling with a conventional handpiece or do not such as those
shown in FIG. 1 at 12a-d.
[0107] Set 10 is shown with four instruments, however, more
instruments may be included so that there is a more gradual
increase in rigidity and ability to aggressively abrade the root
canal as the instruments are sequentially utilized. Also, as shown
by set 10' it is also possible to utilize less instruments.
Advantages of using a set with less instruments is that the set is
less expensive and is simpler to use than sets with more
instruments. The set may even include only two instruments or only
a single instrument may be utilized to clean the operative middle
portion. Accordingly, instruments such as instruments 10a-d or
10a'-c' may be used alone or as part of a set to remove and clean
essentially all pulp material from the operative coronal portion
and the operative middle portion. Such instruments as well as sets
that includes such instruments are additional examples of first
endodontic instrument means for anatomically removing and
anatomically cleaning essentially all pulp material from the
operative middle portion without significantly extending into the
apical root portion.
[0108] The apical portion, as discussed above, is the location in
the root canal of most complications that occur during a root canal
cleaning procedure. The greatest likelihood for the occurrence of
complications such as over thinning of root canal walls,
perforation or extrusion of material from the canal is in the
apical portion. The apical portion is the most likely site for such
complications as apical portions are more complex and delicate
compared to the operative middle portions of teeth. Since such
complications are most likely to occur in the apical portion, it is
advantageous to simplify and ease the cleaning of the apical
portion by first cleaning the operative middle portion.
[0109] It is also highly beneficial to have the material removed
from the operative middle portion in order to minimize the amount
of material that can come out of the root canal to cause problems.
Since the majority of bacteria in an infected root canal is
typically located in the operative middle portion, removal of pulp
material 250 from operative middle portion 262 removes the majority
of bacteria in the pulp canal. Not only is the greatest volume of
bacteria in the operative middle portion but it is also believed
that the concentration is greater in the operative middle portion.
Since a certain minimum threshold must generally be reached for
complications to arise due to microbial presence in a root canal,
removal of the pulp material in the operative middle portion before
cleaning the apical portion significantly reduces the likelihood of
complications such as exposing the surrounding tissue to bacteria
due to overly thinning the root canal, perforation or extrusion of
material from the canal. For example, in the event of an apical
extrusion far less septic material may be expressed during
instrumentation in accordance with present methodology than if the
apical extrusion occurred as a result of cleaning in accordance
with conventional methods wherein files are inserted to the apical
portion before cleaning the operative middle portion. As a result,
removal of the majority of bacteria before cleaning the apical
portion increases the likelihood of successful root canal therapy
in several ways compared with conventional methods. More
particularly, since the aggressive cleaning motions do not occur in
the apical portion, the likelihood of complications is decreased
and if a complication does occur in the apical portion it is less
likely to result in failure of the procedure.
[0110] Since the majority of bacteria in an infected root canal is
typically located in the operative middle portion, it has been
found that after the operative middle portion has been cleaned in
an abrasive manner effective root canal procedures can be completed
by cleaning the apical portion without abrading the apical portion.
More particularly, after removing and cleaning essentially all pulp
material from the operative middle portion of an operative root
canal in conformance with the anatomical shape of the operative
middle portion by flexibly moving an instrument within the
operative middle portion, the root canal procedure can be
effectively completed by merely irrigating the apical portion of
the root canal and then removing the irrigant and debris. This
eliminates the possibility of exposing the surrounding tissue to
bacteria due to overly thinning or perforating the apical portion
of the root canal and minimizes the possibility of extrusion of
material from the canal. Since such complications typically occur
during abrasive instrumentation within the apical portion due to
the delicate and complex structure of the apical portion, the
elimination of the need for abrasive instrumentation in the apical
portion is highly advantageous. Further, this methodology is
particularly advantageous in light of the prior cleaning of the
root canal above the apical portion.
[0111] Another benefit of cleaning the apical portion by irrigating
the apical portion with an irrigant and then removing the irrigant
and debris from the apical portion, is the reduction in the number
of instruments needed to complete the procedure. More particularly,
since instruments adapted for abrading the apical portion are not
necessary but are optionally used, the total instruments used in
performing root canal procedures is reduced.
[0112] In addition to cleaning the apical portion, irrigation is
used to maintain the smear layer in solution within the apical
portion, thereby avoiding smear layer accumulation. Additionally,
it is useful to maintain the debris derived from cleaning the root
canal in suspension to avoid filling the apical portion of the root
canal with a plug. If the apical portion becomes filled, there is
an increased likelihood that the progression may be prevented or
that debris may be pushed out of the tooth.
[0113] The irrigant may be delivered from an irrigation tip such as
angled irrigation tip 320 as shown in FIG. 5A which is attached to
a syringe 390. FIG. 5B shows cannula 360 of irrigation tip 320
extending down into apical portion 264 in close proximity to apex
254b of root canal 252b. Such angled irrigation tips are disclosed
in greater detail in U.S. Pat. No. 6,079,979 entitled Endodontic
Irrigator Tips and Kits which issued to Francesco Riitano and is
owned by Ultradent Products Inc.; the disclosure of which is hereby
incorporated by reference. Another preferred irrigation tip is the
Endo-Eze(.RTM. irrigator tip sold by Ultradent Products, Inc which
has a straight cannula or needle. Examples of suitable
Endo-Eze.RTM. irrigator tips include those which have a 27 gauge
cannula (0.40 mm out diameter), 30 gauge cannula (0.30 mm outer
diameter) and a 31 gauge (0.25 mm outer diameter). In some
circumstances, larger needles may be used. In any event, the needle
or cannula is preferably sufficiently small to avoid binding within
the cannula and also to enable backflow for flushing the apex.
While such particular irrigation devices are preferred, any
conventional irrigation tip and associated delivery device such as
a syringe may be utilized. Other apical portion cleaning
instruments can also be utilized such as pipettes. The irrigator
tips disclosed herein and other suitably shaped narrow tubular
devices, are examples of means for cleaning the apical root
portion, after the pulp material has been essentially removed from
the operative middle portion. More specifically, the irrigator tips
are examples of means for cleaning the apical root portion by
delivering an irrigant into the apical root portion.
[0114] In addition to syringes, such irrigator tips may be coupled
to a Stropko device such as the delivery device disclosed in U.S.
Pat. No. 5,378,149 issued to John J. Stropko which is hereby
incorporated by reference. Syringes and the Stropko device are
examples of delivery devices. These same devices are examples of
irrigant delivery devices when coupled with an irrigator tip that
enables the delivery devices to easily access the root canal. While
these irrigant delivery devices are particularly useful when
cleaning the apical portion, all of these irrigant delivery devices
may also be used in irrigating the canal at any appropriate time
during the root canal procedure. Note that syringes and other
delivery devices such as a Stropko delivery device are examples of
means for delivering irrigants and/or removing irrigants and any
remaining debris via the irrigator tip or means for cleaning the
apical root portion.
[0115] Pipettes are a less preferred alternative to the use of
irrigation tips as apical portion cleaning instruments to deliver
irrigants into the root canal. Such conventional pipettes are well
known in endodontistry and are used to deliver irrigants by
squeezing part of the pipette. The pipettes may be prefilled or
used with a separate reservoir or container of lubricant. A pipette
is an example of an integral irrigant delivery device while an
irrigator tip coupled to a syringe or a Stropko device is an
example of a separable irrigant delivery device. Such integral
irrigant delivery devices are additional examples of means for
cleaning the apical root portion or more specifically, means for
cleaning the apical root portion by deliverying an irrigant into
the apical root portion.
[0116] These same irrigant delivery devices are typically used to
remove the irrigant and any remaining debris. For example, the
syringe may be used to aspirate the irrigant and any remaining
debris out of the apical portion. Similarly, a pipette may apply
appropriate suction to remove the irrigant and any remaining
debris. The endodontic irrigator tip may also be coupled to other
conventional aspiration devices. Other irrigant removal devices
include conventional paper points.
[0117] Although, the irrigant preferably is capable of dissolving
or disrupting soft tissue remnants to permit their removal, the
irrigant may be any suitable liquid such as water or various
alcohols. More particularly, although some degree of debridement is
preferred, any fluid may be used to flush debris from the root
canal. General examples of appropriate irrigants include hydrogen
peroxide, primarily for use in the canals of living teeth, or
sodium hypochlorite, primarily for the canals in necrotic teeth.
The preferred irrigant is the aqueous sodium hypochlorite solution
sold as ChlorCid.RTM. by Ultradent Products, Inc which contains
about 2.5-3% NaOCL. The irrigant may also be a chelator or calcium
remover such as EDTA solutions or citric acid solutions. A
preferred chelator is sold as File-Ezet by Ultradent Products Inc.
which is a 19% EDTA water soluble viscous solution. File-Eze.RTM.
is a preferred chelator as it is also a lubricant.
[0118] As indicated above, it may be necessary in some
circumstances to improve the access into the apical root portion
before cleaning the apical root portion of the root canal. More
particularly, it may be beneficial or necessary to widen the tract
of the root canal to provide access for thin irrigation needles.
This may be achieved by widening the transition between the
operative middle portion 262 and the apical portion 264 or by
widening the entire apical portion such that a thin irrigation
needle can access the apical portion as needed. Thin irrigation
needles typically have a diameter no smaller than about 0.30 mm so
it may be necessary to increase the diameter of portions of the
root canal up to about 0.35 mm or even up to about 0.40 mm,
particularly within the region of the boundary between the
operative middle portion and the apical root portion. Note that the
diameter need only be slightly larger than a thin irrigation needle
in order to provide adequate access. Improving access into the
apical portion not only enables such irrigation needles to move as
needed, it also reduces the likelihood that the thin irrigation
needles will be blocked. Although FIG. 3 depicts file 74d inserted
into apical portion 264 of root canal 252a and cleaning the apical
portion, use of instruments 40a or 40b of optional set 40 is
achieved in essentially the same fashion. When utilized to widen
the access into the apical root portion of a root canal, file 40a
is first introduced followed sequentially by file 40b.
[0119] Instrument 40a has a file 44a with smooth shank portion 46a,
a square portion 47a, an abrading portion 49a and a file tip 48a.
As shown, the smooth shank portion 46a is the top section of file
44a and a handle 42 is positioned on shank portion 46a. Smooth
shank portion 46a tapers to square portion 47a which is between
shank portion 46a and abrading portion 49a. A file instrument such
as file instrument 40a or a set of file instruments such as 40a and
40b comprises a second endodontic instrument means for improving
access into the apical root portion after the pulp material has
been essentially removed from the operative middle portion by the
first endodontic instrument means.
[0120] It is not necessary for the entire apical portion to be
widened up to about 0.35 mm or about 0.40 mm; just enough of the
apical portion should be widened so that the irrigants can be
delivered as needed. However, the length of files used to widen the
apical portion is preferably sufficient to at least approximately
reach the apex. Accordingly, the top of the abrading portion may be
flared to enable the upper area of the apical portion to be widened
up to about 0.40 mm while the tip diameter which is at or near the
apex is preferably significantly smaller. Note that in addition to
abrading at least the top of the apical portion, it may also be
necessary to widen the diameter in the region of the base of the
operative middle portion. Before widening the apical portion of the
root canal, it is preferable to make a predetermination of the
desired diameter. This predetermination is preferably made in light
of morphometric data such as average diameters, wall thicknesses,
etc. for the particular root canal being cleaned.
[0121] As indicated above, the length of a file such as files 44a
and 44b is preferably sufficient such that when the file is
inserted into the root canal the tip can at least approximately
reach the apex and the abrading portion of the file can improve the
access into the apical portion of the root canal. Although files
used to improve the access into the apical root portion may be long
enough to approximately reach the apex, the files can be used to
improve the access as long as the files can reach the bottom of the
operative middle portion and the top of the apical root portion.
Such file lengths are typically within a range from about 8 mm to
about 35 mm, more typically in a range from about 14 mm to about 35
mm and most typically in a range from about 12 mm to about 33
mm.
[0122] Each file of the file instruments designed for improving
access to the apical root portion of a root canal is configured to
have an abrading portion such as abrading portions 49a-b along at
least a portion of the length of the file. The entire length of
each file can be configured with an abrading portion, however, the
abrading portion preferably extends from the tip part way upward
towards the top end such that the remainder of the file is
relatively smooth. More particularly, each file is preferably
configured with an abrading portion along less than about half of
the length of the file and more preferably about one-third of the
length between the tip and the top end. The abrading portion is
preferably long enough so that the entire apical portion can be
abraded as well as at least the bottom of the operative middle
portion. The length of the abrading portion is generally within a
range from about 1 mm to about 35 mm, preferably in a range from
about 2 mm to about 16 mm, more preferably in a range from about 3
mm to about 10 mm, and most preferably in a range from about 5 mm
or about 6 mm Note that stops such as stop 140 may alternatively be
utilized with instruments used to improve the access into the
apical root portion. The abrading portions may have a similar or
identical configuration to the abrading portions disclosed herein
for cleaning either the operative middle portion of the root canal
or the apical root portion.
[0123] In an optional set of instruments used to improve the access
into an apical root portion, the file tips of the instruments
preferably all have about the same diameter. The diameter of the
tips, such as the diameter of tips 48a-b, is generally within a
range from about 0.06 mm to about 1 mm, however, the tips
preferably have a diameter of about 0.08 mm. In a less preferred
embodiment, the tip diameter of each file may also increase
sequentially. The tips can have a similar or identical
configuration to the tips of the files disclosed herein for
cleaning either the operative middle portion of the root canal or
the apical root portion. However, the tips are preferably
rounded.
[0124] The diameter of the abrading portions preferably increases
from the tips towards the top of the abrading portions. The
diameter of the abrading portion at the top is preferably within a
range from about 0.1 mm to about 0.4 mm and is more preferably in a
range from about 0.25 mm to about 0.4 mm Each successive file
preferably has an abrading portion which is successively larger in
diameter at the top of the abrading portion than the abrading
portion of the preceding file. Accordingly, a set may have files
with abrading portions having the following respective top
diameters: about 0.2 mm, about 0.25 mm, about 0.3 mm and about 0.35
mm. Each abrading portion in such a set has a different taper. The
abrading portion may also have essentially the same taper so that
the taper of the shank portions remains essentially constant as the
different files in the set are sequentially inserted. However, the
abrading portions and the shank portions of the files may have any
suitable configuration.
[0125] As mentioned above, the apical portion may be alternatively
cleaned by abrading the apical portion. Typically, the instruments
used to optionally improve the access into the apical portion, the
apical portion access instruments, have the same lengths as the
instruments optionally used thereafter to abrade the apical portion
so that the entire apical portion is first widened and then cleaned
in an abrasive manner. The instruments, however, have different tip
diameters and tapers along their respective abrading portions. The
apical portion access instruments generally have much smaller tip
diameters and much greater tapers than the instruments used to
abrasively clean the apical portion. Refer to Example 1 for a
discussion of specific instruments utilized and to observe the
alteration of the apical portion after the apical portion widening
phase and the apical portion cleaning phase.
[0126] The apical portion cleaning instruments are preferably more
flexible than the instruments used to clean the operative coronal
portion and the operative middle portion since the apical portions
tend to be more curved. While stainless steel may be utilized, the
files are preferably formed from nickel/titanium or a stainless
steel alloy such as a precipitation hardenable stainless steel,
particularly 17-4PH stainless steel that has not been aged or
subjected to heat treatment. While files can be formed from these
same metals that are utilized in the operative coronal portion and
the operative middle portion, such metals are particularly suited
for use in the apical portion as such metals provide optimal
flexibility. Note also that the apical portion cleaning instruments
are typically manually moved so that these flexible files can be
carefully maneuvered. The instruments used to optionally improve
the access into the apical portion may also be formed from any of
these metals.
[0127] Before the apical root portion is abrasively cleaned, it is
preferable to obtain further x-ray images while an instrument is
inserted into a root canal to determine the desired working length
of the instrument. In establishing the working length, the state of
the apex and the periapical tissues should also be evaluated, in
accordance with the following guidelines. For living or necrotic
teeth "without rearrangement of the apex" or apical rarefaction,
the instrument(s) should be kept no closer than 2 mm from the apex
as shown on the x-ray image. Conversely, for necrotic teeth with
apical autolysis, the preparation work may be performed up to a
distance of 1 mm from the apex as shown on the x-ray image. The
predetermination of the widening of the canal leading to the apex,
and the widening of each root canal for polyradiculated teeth,
should be made bearing in mind typical morphometric
configurations.
[0128] In most cases, the radicular apex contains the final segment
of the main canal, which divides into a delta configuration. This
structure is hard to detect with x-rays. Therefore, the morphology
of the dental apex is unpredictable, and the location of the
junction between the cementum and dentin in any endodontic apex is
random Likewise random is the hypothetical apical constriction that
can be detected by the most expert professionals. A degree of
confidence can be obtained through the use of electronic
measurement devices in living canals that have not been treated
with liquid medications, but only when the foramen has been passed,
in order to be subsequently withdrawn into the canal with a probe
instrument. This maneuver should be avoided in necrotic canals,
because of the risk of carrying germs beyond the apex.
[0129] The guidelines discussed above should be kept in mind when
redetermining the approximate working length to the apex after the
operative middle portion has been prepared. It is necessary to
redetermine the working length as the working length has likely
changed due to the instrumentation of the operative middle
portion.
[0130] Set 70 is shown with twelve instruments. However, in use
only 1-3 instruments are typically utilized. If a file is inserted
and it is apparent to the practitioner that the file is not
engaging the walls of the root canal in the apical portion, then a
larger file is inserted. While instrumenting the root canal with
only this instrument may be sufficient, it is often necessary to
utilize one or two additional instruments with successively larger
files. So for example, if file 70b or 70c is first introduced into
the apical root portion then it is followed by then next larger
file such as 70c or 70d.
[0131] Each file instrument 70a-l comprises a handle 72a-l
connected to a file 74a-l. Each file 74 has a top end where the
file joins handle 72. Each file terminates at a tip 78a-l located
opposite the top end of the file. Each file 74 has a smooth shank
portion 76, a square portion 77 and an abrading portion 79. A file
instrument such as file instrument 70a or a set of file instruments
such as 70a-l comprises a third endodontic instrument means for
optionally, abrasively cleaning and removing essentially all
remaining pulp material from the apical root portion after the pulp
material has been essentially removed from the operative middle
portion. Note that the endodontic instrument means for abrasively
cleaning and removing essentially all remaining pulp material from
the apical root portion after the pulp material has been
essentially removed from the operative middle portion and the means
for cleaning the apical root portion by delivering an irrigant into
the apical portion after the pulp material has been essentially
removed from the operative middle portion are both examples of
means for cleaning the apical root portion after the pulp material
has been essentially removed from the operative middle portion.
[0132] Exemplary dimensions of files 70a-l are provided below in
detail in Example 1 of the Examples of the Preferred Embodiment.
The file of each apical portion file instrument is an example of
operative apical portion instrument means for movement within the
apical root portion so as to effect removal and cleaning of pulp
material as the file instrument means is operatively moved.
[0133] Each file 74 of the file instruments designed for abrasively
cleaning the apical root portion of a root canal is configured to
have an abrading portion 79 along at least a portion of the length
of file 74. Like files 44, the entire length of each file 74 can be
configured with an abrading portion 79, however, abrading portion
79 preferably extends from tip 78 part way upward towards top end
73 such that the remainder of file 74 is relatively smooth. More
particularly, each file is preferably configured with an abrading
portion along less than about half of the length of the file and
more preferably about one-third of the length between tip 78 and
top end 73. The abrading portion 79 can have a similar or identical
configuration to the abrading portions of the file used to clean
the operative middle portion of the root canal or to improve the
access into the apical root portion.
[0134] The length of an optional apical portion abrading file such
as files 74a, 74b and 74c is sufficient such that when the files
are inserted into the root canal the tips can at least
approximately reach the apex and the abrading portion 79 of the
files can substantially contact and abrasively clean the pulp
material in the apical portion of the root canal. Such file lengths
are generally within a range from about 8 mm to about 35 mm, more
typically in a range from about 14 mm to about 35 mm and most
typically in a range from about 12 mm to about 33 mm. The length of
the abrading portion is generally within a range from about 1 mm to
about 35 mm, more preferably in a range from about 2 mm to about 16
mm and most preferably in a range from about 3 mm to about 6 mm.
Note that stops such as stop 140 may alternatively be utilized with
instruments used to abrasively clean the apical root portion.
[0135] The diameter of the abrading portion is generally within a
range from about 0.06 mm to about 1.4 mm. As shown in FIG. 1, each
successive file has an abrading portion, identified as 79a-l, which
is successively larger in diameter at the top of the abrading
portion than the abrading portion of the preceding file.
[0136] The diameter of the tips 78a-c of each optional apical
portion abrading file may be increased incrementally such that each
sequentially utilized abrasive cleaning instrument has a slightly
larger tip diameter than the preceding instrument as shown in FIG.
1 or the tips diameters may be about equal in diameter. Tips 78a-l
can have any configuration, however, tips 78a-l are preferably
rounded with minimal cutting capability to decrease the likelihood
of ledging.
[0137] The diameter at the top end of the file is shown being
greater than the diameter of the abrading portion. However, the
diameter at the top end of the file can also be equal to or less
than the diameter of abrading portion 79 or tip 78.
[0138] Note that all of the abrading portions 79a-l of files 74a-l
may have the same taper or a set may include files with abrading
portions having more than one taper. The taper may also increase
from file to file. In a preferred embodiment, however, the last
file used to instrument in the apical portion preferably has a
taper that is greater than the conventional ISO taper of 0.2 to
enable the gutta percha points having a taper of 0.2 to be easily
inserted.
[0139] The abrading portions of files used to clean the apical
portion or to improve the access into apical portion may be formed
in any manner such as those described above in reference to the
abrading portions of files used to clean the operative middle
portion. The abrading portion 79 preferably has few spirals such
that the action of abrading portion 79 against the walls or
surfaces of the apical portion of the root canal is relatively
gentle. Such an abrading portion is less aggressive as fewer
spirals results in tines that have a wider angle.
[0140] When cleaning the apical portion 264 as shown in FIG. 3, the
apical root portion file instruments are generally moved in a
different pattern compared to the operative middle portion file
instruments due primarily to the different perimeter anatomies of
the two portions. A root canal generally becomes more cylindrical
towards the apical portion such that a root canal with a perimeter
anatomy that is essentially elliptical in shape within the
operative middle portion tapers to an essentially cylindrically
shaped perimeter anatomy within the apical portion.
[0141] Due to the more cylindrical anatomy of an apical root
portion, it becomes much less necessary, and virtually impossible
to flex a rotating file in a milling motion. It is generally
adequate to merely rotate the file within the apical root portion
and/or move the file in a longitudinal motion. More specifically,
after the file reaches the apex or approximately reaches the apex,
the file is preferably moved upward while simultaneously being
rotated, and it is withdrawn in order to be cleaned before being
reintroduced.
[0142] Since the instruments used to clean the apical portion and
to improve the access into the apical portion are typically moved
by hand, they have a handle adapted for such use as shown at 42a-b
and 72a-72l while the instruments used to clean the operative
middle portion have handles 12a-d adapted for use with an
endodontic handpiece. The file instruments of the present invention
can, however, be utilized with any suitable handle configuration.
All of the handles disclosed herein are examples of end means for
grasping and operatively moving a file in an abrasive action.
[0143] Since an apical portion file is generally not moved around
the perimeter as in cleaning the operative middle portion, the
center of motion, such as the center of rotation, of the file
generally corresponds with the center of the root canal. In
contrast, the center of motion during cleaning of the operative
middle portion is at various locations as the file is moved around
the root canal.
[0144] The files used to optionally clean the apical root portion
in an abrasive manner can be designed for primarily longitudinal
movement, rotational movement or combinations thereof Since it is
generally not necessary to flex a file when cleaning the apical
root portion as the apical root portion is typically more round
than other sections of a root canal, apical root portion files need
not necessarily have the same properties as the operative middle
portion files in terms of flexibility, rigidity and resilience. The
files used to clean the apical portion are, however, preferably
sufficiently flexible to adjust to the anatomy or structure of a
root canal in a manner that enables the tip of the file to reach
the apex. The files also preferably have sufficient rigidity to
apply pressure against the walls or surfaces of the root canal as
the abrading portion of the file is urged against the walls of the
root canal and simultaneously moved in a cleaning motion even after
the file has moved throughout the length of the root canal.
Additionally, a file configured for use in an apical root portion
preferably has adequate resilience to avoid being substantially
deformed as the file passes through a root canal and also as the
abrading portion is applied against the walls of the root
canal.
EXAMPLES OF THE PREFERRED EMBODIMENTS
[0145] Examples 1-2 are hypothetical examples presented solely to
illustrate some embodiments of the present invention. Note that
reference is made in Example 1 to FIG. 1 and FIGS. 6A-D. Example 1
provides a discussion of the use of the three sets of instruments
identified at 10, 40 and 70 in FIG. 1 to prepare a root canal.
Example 2 provides a discussion of the use of set 10 to clean the
operative middle portion followed by cleaning of the apical root
portion through delivery of an irrigant. The shapes and dimensions
of the embodiments of endodontic file instruments provided herein
are merely illustrative, but not limiting, of the variety of
endodontic file instruments that are manufactured according to the
present invention. The hypothetical examples are not to be
construed as limiting the spirit and scope of the invention as
these hypothetical examples were produced in furtherance of
reducing the present invention to practice.
Example 1
[0146] This example describes, in relation to FIG. 1 and FIGS.
6A-6D, an exemplary system and method for cleaning a root canal
after the root canal has been properly accessed. After a tooth has
been identified as requiring root canal therapy, an x-ray image is
obtained in order to determine the state of health of a tooth as
well as the structure and anatomical characteristics of the tooth.
After all carious tissue and any old fillings have been removed, a
dam is installed. The pulp chamber is then opened so that adequate
access can be gained to the anatomical root canal. Access is gained
by removing the top of the pulp chamber, preferably with an
appropriate diamond bur instrument. The contents in the pulp
chamber are then removed with the aid of appropriate irrigants.
Examples of appropriate irrigants include hydrogen peroxide,
primarily for use in the canals of living teeth, or sodium
hypochlorite, primarily for the canals in necrotic teeth. If
desired a cuspidectomy may be performed.
[0147] It is then preferable to remove or reduce dentinal or enamel
protrusions or irregularities such as dentinal shelves, that may
obscure or hinder access of instruments into the operative root
canal by rectification of such protrusions with an appropriate
instrument which preferably utilizes diamonds for abrasion. FIG. 6A
depicts a tooth 240' before the removal of dentinal shelf 266'
above root canal 252a'. Dotted line 265' in FIG. 6A depicts the
desired realignment through rectification in order to provide
greater access for instrumentation during the subsequent phases.
Rectified root canal 252a' depicted in FIGS. 6B-D after subsequent
phases shows that rectification would enable an instrument to be
inserted in a relatively straight manner though the operative
coronal portion 260 and the operative middle portion 262. Although,
an instrument would need to flex within the apical portion 264 of
root canal 252a' due to its curvature, the required flexing is
minimized as a result of the removal of dentinal shelf 266' above
root canal 252a'. Since the apical portion of root canal 252b' is
essentially straight, rectification of dentinal shelf 266' above
root canal 252b' would also enable an instrument to be inserted
down to apex 254b' through the apical portion 264' in an
essentially straight configuration.
[0148] Note that pulp material is not shown in FIGS. 6A-D so that
the changes to pulp canal 252a' are clearly visible after each
phase. As discussed hereinbelow, FIGS. 6B-D respectively depict
root canal 252a' of tooth 240' after cleaning operative coronal
portion 262, after widening apical portion 264 and after cleaning
apical portion 264.
[0149] After any necessary rectification, the working length is
determined for the files used to clean the operative middle
portion. The appropriate working length is determined by
radiographically identifying the length of the operative root canal
and then subtracting 3 mm from the length identified from the x-ray
image. It is necessary to subtract 3 mm from the overall x-ray
length in order to compensate for any distortions in the x-ray
image and to avoid interfering with the apical portion while the
operative middle portion is being prepared. After identifying the
length of the root canal of a tooth and determining the working
length of the files to be used, instruments can then be selected
which have a length such that essentially all pulp material can be
anatomically cleaned from the operative middle portion of a root
canal without significantly removing pulp material from the apical
root portion.
[0150] Operative Middle Portion Phase and Related Sets of
Instruments
[0151] Tables 1A-1D presented hereinbelow describe the dimensions
of four different set of instruments which can be used to clean the
operative middle portion in different teeth depending on the
particular operative root canal length. These four sets are
preferably sold as part of a kit. Although, the kit includes
several sets of instruments, only one set of instruments is
typically used for cleaning the operative middle portion. The
practitioner selects from several sets in the kit depending on the
particular length of the operative coronal portion and the
operative middle portion. The instruments in Tables 1A-1D are
designed to have a working length that is adjustable depending on
the placement of a stop such as stop 140 or the position of the
handle within the chuck of an endodontic handpiece. Accordingly,
the working lengths for the instruments in Tables 1A-1D are
respectively 15-18 mm, 19-22 mm, 23-26 mm, and 27-30 mm. The
operative middle portion instruments in each set are formed from
stainless steel.
1TABLE 1A Operative Middle Portion Instruments (15-18 mm) Total
Abrading Shank Diameter at Shank Length Portion Portion Tip the top
of the Portion Abrading Instrument of the File Length Length
Diameter Abrading Diameter Portion Number (L.sub.2 + L.sub.3)
(L.sub.2) (L.sub.3) (D.sub.1) Portion (D.sub.3) (D.sub.4) Taper 10a
18 mm 15 mm 3 mm 0.10 mm 0.55 mm 0.50 mm 0.025 10b 18 mm 15 mm 3 mm
0.13 mm 0.76 mm 0.70 mm 0.035 10c 18 mm 15 mm 3 mm 0.13 mm 1.05 mm
0.90 mm 0.051 10d 18 mm 15 mm 3 mm 0.13 mm 1.17 mm 1.00 mm
0.058
[0152]
2TABLE 1B Operative Middle Portion Instruments (19-22 mm) Total
Abrading Shank Diameter at Shank Length Portion Portion Tip the top
of the Portion Abrading Instrument of the File Length Length
Diameter Abrading Diameter Portion Number (L.sub.2 + L.sub.3)
(L.sub.2) (L.sub.3) (D.sub.1) Portion (D.sub.3) (D.sub.4) Taper 10a
22 mm 19 mm 3 mm 0.10 mm 0.65 mm 0.60 mm 0.025 10b 22 mm 19 mm 3 mm
0.13 mm 0.90 mm 0.80 mm 0.035 10c 22 mm 19 mm 3 mm 0.13 mm 1.14 mm
1.00 mm 0.046 10d 22 mm 19 mm 3 mm 0.13 mm 1.45 mm 1.30 mm
0.060
[0153]
3TABLE 1C Operative Middle Portion Instruments (23-26 mm) Total
Abrading Shank Diameter at Shank Length Portion Portion Tip the top
of the Portion Abrading Instrument of the File Length Length
Diameter Abrading Diameter Portion Number (L.sub.2 + L.sub.3)
(L.sub.2) (L.sub.3) (D.sub.1) Portion (D.sub.3) (D.sub.4) Taper 10a
26 mm 23 mm 3 mm 0.10 mm 0.78 mm 0.70 mm 0.026 10b 26 mm 23 mm 3 mm
0.13 mm 0.88 mm 0.80 mm 0.029 10c 26 mm 23 mm 3 mm 0.13 mm 1.12 mm
1.00 mm 0.038 10d 26 mm 23 mm 3 mm 0.13 mm 1.43 mm 1.30 mm
0.050
[0154]
4TABLE 1D Operative Middle Portion Instruments (27-30 mm) Total
Abrading Shank Diameter at Shank Length Portion Portion Tip the top
of the Portion Abrading Instrument of the File Length Length
Diameter Abrading Diameter Portion Number (L.sub.2 + L.sub.3)
(L.sub.2) (L.sub.3) (D.sub.1) Portion (D.sub.3) (D.sub.4) Taper 10a
30 mm 27 mm 3 mm 0.10 mm 0.85 mm 0.80 mm 0.025 10b 30 mm 27 mm 3 mm
0.13 mm 1.00 mm 0.90 mm 0.029 10c 30 mm 27 mm 3 mm 0.13 mm 1.21 mm
1.10 mm 0.036 10d 30 mm 27 mm 3 mm 0.13 mm 1.54 mm 1.40 mm
0.047
[0155] As provided in this example, the instruments having a
working length of 19-22 mm as presented in Table 1B are selected
for use in a tooth due to the combined length of the operative
coronal portion and the operative middle portion of the operative
root canal which is in the range of 19-22 mm. More particularly,
the root canal of the tooth is slightly longer than about 25 mm so
the full 22 mm of the working length is utilized. The set of
instruments for cleaning the operative middle portion detailed in
Table 1B corresponds with the set of instruments shown in FIG. 1 at
10. Since only one set of instruments is used to clean the
operative middle portion only one set is shown in FIG. 1 at 10.
[0156] After set 10, as detailed in Table 1B, is selected, the pulp
chamber is flooded with an irrigation fluid or filled with a
chelating lubricant gel, if the canal is atresic. The instruments
in set 10 are then attached to a handpiece to move the instruments
in either a rotating or reciprocating motion. These instruments can
also be manually moved.
[0157] File 10a is first introduced into the operative middle
portion followed sequentially by file instrument 10b, 10c and then
10d. Instruments 10a-d are each urged against the root canal for
about one minute in conformance with the anatomy of the root canal.
More particularly, the instruments are applied to the perimeter of
the canal, acting on any protuberances or jagged edges in order to
rectify the first two portions, the operative middle portion and
the operative coronal portion, while still conforming to the
anatomy of the canal.
[0158] Note that, as shown in FIG. 1, the diameter at the top of
each abrading portion 19a-d is incrementally greater than the
diameter of the top of the abrading portion of the preceding file.
Accordingly, the diameter of the top end of each successive file
introduced into the operative middle portion is greater than the
diameter of the top end of each preceding file. This provides for
an increased surface area for cleaning the root canal and the
ability to more rapidly widen the root canal. The practitioner is
able to move the instruments around the perimeter of the operative
middle portion of the root canal using the contours of the
operative middle portion as a guide for the movement of the
instrument such that the original anatomy is enlarged and not
significantly altered.
[0159] The tip diameter of each file in set of operative middle
portion instruments are essentially the same. More particularly,
the instruments in each set detailed above has a first instrument
10a with a tip diameter of 0.10 mm while the instruments
sequentially used thereafter have a tip diameter of 0.13 mm.
Accordingly, the flexibility of the lower half remains essentially
constant which is ideal since these portions of the root canal
being cleaned tapers from a laminar configuration to a more round
shape.
[0160] After cleaning the operative middle portion, the root canal
may appear as does root canal 252a' of tooth 240 shown in FIG. 6B.
FIG. 6B shows that dentinal shelf 266' has been fully rectified.
The other contours of root canal 252a' have been followed to clean
operative middle portion 262. As a result, the diameter of the root
canal in operative middle portion 262 has been widened, although,
the original perimetrical anatomy has not been substantially
altered.
[0161] Apical Portion Widening Phase and Related Sets of
Instruments
[0162] A probe is then inserted to the apex of the root canal and
another x-ray image is obtained. After the length has been
determined the accessibility of the apical portion is assessed. If
the apical portion is initially to small to permit entry of an
irrigation cannula then an optional set of instruments is selected
for use in improving the access into the apical root portion or
stated otherwise to enlarge the constricted region between the
operative middle portion and the apical portion. This is achieved
by manually moving one or more instruments until the transition
zone between the operative middle portion and the apical root
portion has been appropriately instrumented to have a diameter of
about 0.40 mm, which is suitable for accommodating the diameters of
the smallest irrigation needles.
[0163] Again the practitioner has a comprehensive kit with several
sets of instruments which are designed for improving access into
the apical root portion after the pulp material has been removed
from the operative middle portion of a root canal. Each set is
designed for use in a tooth with a different operative root canal
length. Accordingly, only one set from the kit is selected for use
in operative root canal based on the length of the particular
anatomical root canal being treated.
[0164] Tables 2A-2C detail the dimensions of instruments with file
lengths which are respectively 21 mm, 25 mm and 30 mm. In this
example, the set presented in Table 2B is selected since a tooth is
being instrumented with a root canal that is slightly longer than
about 25 mm. The set presented in Table 2B is shown in FIG. 1 as
set 40. Note, however, with the exception of length, the
instruments detailed in Table 2A and Table 2C would appear just
like set 40. The files of the instruments in the sets detailed in
Tables 2A-2C are formed from a suitable material such as nickel
titanium or stainless steel.
5TABLE 2A Apical Widening Instruments (21 mm) Total Abrad. Square
Round Abrad Square Shank Length of Portion Portion Portion Tip
Portion Portion Portion Inst. File Length Length Length Diam. Diam.
Diam. Diam. No. (L.sub.1 + L.sub.3 + L.sub.4) (L.sub.1) (L.sub.4)
(L.sub.3) (D.sub.1) (D.sub.2) (D.sub.3) (D.sub.4) Taper 40a 21 mm 5
mm 11 mm 5 mm 0.08 mm 0.28 mm 0.30 mm 0.80 mm 0.04 40b 21 mm 5 mm
11 mm 5 mm 0.08 mm 0.38 mm 0.40 mm 1.1 mm 0.06
[0165]
6TABLE 2B Apical Widening Instruments (25 mm) Total Abrad. Square
Round Abrad Square Shank Length of Portion Portion Portion Tip
Portion Portion Portion Inst. File Length Length Length Diam. Diam.
Diam. Diam. No. (L.sub.1 + L.sub.3 + L.sub.4) (L.sub.1) (L.sub.4)
(L.sub.3) (D.sub.1) (D.sub.2) (D.sub.3) (D.sub.4) Taper 40a 25 mm 5
mm 15 mm 5 mm 0.08 mm 0.28 mm 0.30 mm 0.90 mm 0.04 40b 25 mm 5 mm
15 mm 5 mm 0.08 mm 0.38 mm 0.40 mm 1.3 mm 0.06
[0166]
7TABLE 2C Apical Widening Instruments (30 mm) Total Abrad. Square
Round Abrad Square Shank Length of Portion Portion Portion Tip
Portion Portion Portion Inst. File Length Length Length Diam. Diam.
Diam. Diam. No. (L.sub.1 + L.sub.3 + L.sub.4) (L.sub.1) (L.sub.4)
(L.sub.3) (D.sub.1) (D.sub.2) (D.sub.3) (D.sub.4) Taper 40a 30 mm 5
mm 20 mm 5 mm 0.08 mm 0.28 mm 0.30 mm 1.1 mm 0.04 40b 30 mm 5 mm 20
mm 5 mm 0.08 mm 0.38 mm 0.40 mm 1.6 mm 0.06
[0167] Each file has three sections including a smooth shank
portion, a square portion and an abrading portion. The smooth shank
portion enables stops be positioned on the file to adjust the
working length of the file. Each smooth shank portion of each file
has a length of about 5 mm with various diameters. The instruments
can be used for all operative lengths that are likely to be
encountered in clinical practice through the positioning of the
stops at the predetermined lengths. While the instruments can be
offered in a more expanded series of millimetrically different
lengths, the use of stops is acceptable, particularly since, these
instruments are manually moved.
[0168] In each set, the diameter at the top of the square portion
of instrument number 40a and instrument number 40b is respectively
0.30 mm and 0.40 mm. The abrading portion is formed by twisting the
square section so that the abrading portion has a K-file
configuration. The instruments in each set all have the same tip
diameters. The taper of the files from the tip (D.sub.1) to the
diameter at the top of the square portion (D.sub.3) remains
constant and is respectively 0.04 and 0.06 for instrument number
40a and instrument number 40b in each set.
[0169] Preferably, instrument 40a is first utilized and then
instrument 40b to obtain, in a gradual manner, the desired
enlargement of the specific transition zone between the operative
middle portion and the apical portion. This enlargement is also
preferably achieved without significantly changing the diameter of
the apical portion of the canal. Accordingly, the tip diameter
(D.sub.1) of the various instruments in this set remains constant
while the diameter at the top of the cutting area or abrading
portion (D.sub.2), located 5 mm from the tip, is graduated from one
instrument to the next, reaching a maximum diameter of 0.38 mm. The
rest of the shaft, up to the handle, does not have a cutting
surface. To the extent that these instruments are used to expand
the apical portion of the canal, the practitioner should constantly
bear in mind the average diameters of the canals and the average
thicknesses of the parietal walls at the apex.
[0170] After widening the apical portion of the root canal with the
set shown at 40 in FIG. 1 and as detailed in Table 2B, the root
canal may appear as does root canal 252a' in FIG. 6C with a widened
transition into apical portion 264. More particularly, the region
of root canal 252a' extending from the bottom of operative middle
portion 262 to the top half of apical portion 264 has been
noticeably widened. The bottom half of apical portion 264 has also
been widened but to a much lesser degree.
[0171] Apical Portion Cleaning Phase and Related Sets of
Instruments
[0172] After the access into the apical portion has been adequately
widened as discussed hereinabove and as shown in FIG. 6C, the
apical portion is cleaned. Cleaning is halted as the working length
is determined by the operator. The practitioner should determine
this length beforehand, based on the biological condition of the
apico-periapical region, in terms of typical morphometrics of the
diameters and thicknesses at the apex, and in accordance with the
amount of widening to be applied to the apical portion of the
canal.
[0173] Again sets of instruments are provided with each set having
a different length. Three sets of instruments are described
hereinbelow which are designed for removing and cleaning
essentially all pulp material from the apical root portion after
access into the apical root portion has been improved by a set of
instruments such as set 40 detailed in Table 2B. In some instances,
the instruments described in this example can also be used to clean
the pulp material from the root canal immediately after the
operative middle portion has been cleaned by a set of instruments
such as the sets presented in Table 1B. P Tables 3A-3C detail the
dimensions of instruments with file lengths which are respectively
21 mm, 25 mm and 30 mm. However, please note that only instruments
from set detailed in Table 3B are used in the tooth being cleaned
in this example as the files in this set having the appropriate
length. Instruments 70a-l in the set presented in Table 3B
respectively correspond with instruments 70a-l of set 70 shown in
FIG. 1. The instruments in set 70 have a similar appearance as the
instruments in set 40. The sets of instruments presented in Table
3A and 3C have a similar appearance to instruments detailed in
Table 3B and shown at 70, however, the files have different
lengths. In addition to the lengths and diameters of the various
portions, the taper of each file from the tip (D.sub.1) to the
diameter at the top of the square portion (D.sub.3) is provided in
each table.
8TABLE 3A Apical Cleaning Instruments (21 mm) Total Abrad. Square
Round Abrad Square Shank Length of Portion Portion Portion Tip
Portion Portion Portion Inst. File Length Length Length Diam. Diam.
Diam. Diam. No. (L.sub.1 + L.sub.3 + L.sub.4) (L.sub.1) (L.sub.4)
(L.sub.3) (D.sub.1) (D.sub.2) (D.sub.3) (D.sub.4) Taper 70a 21 mm 5
mm 11 mm 5 mm 0.10 mm 0.20 mm 0.42 mm 0.50 mm 0.02 70b 21 mm 5 mm
11 mm 5 mm 0.15 mm 0.25 mm 0.47 mm 0.50 mm 0.02 70c 21 mm 5 mm 11
mm 5 mm 0.20 mm 0.30 mm 0.52 mm 0.60 mm 0.02 70d 21 mm 5 mm 11 mm 5
mm 0.25 mm 0.375 mm 0.65 mm 0.70 mm 0.025 70e 21 mm 5 mm 11 mm 5 mm
0.30 mm 0.425 mm 0.70 mm 0.70 mm 0.025 70f 21 mm 5 mm 11 mm 5 mm
0.35 mm 0.475 mm 0.75 mm 0.80 mm 0.025 70g 21 mm 5 mm 11 mm 5 mm
0.40 mm 0.525 mm 0.80 mm 0.80 mm 0.025 70h 21 mm 5 mm 11 mm 5 mm
0.50 mm 0.625 mm 0.90 mm 0.90 mm 0.025 70i 21 mm 5 mm 11 mm 5 mm
0.60 mm 0.725 mm 1.0 mm 1.0 mm 0.025 70j 21 mm 5 mm 11 mm 5 mm 0.70
mm 0.825 mm 1.1 mm 1.1 mm 0.025 70k 21 mm 5 mm 11 mm 5 mm 0.80 mm
0.925 mm 1.2 mm 1.2 mm 0.025 70l 21 mm 5 mm 11 mm 5 mm 1.0 mm 1.125
mm 1.4 mm 1.5 mm 0.025
[0174]
9TABLE 3B Apical Cleaning Instruments (25 mm) Total Abrad. Square
Round Abrad Square Shank Length of Portion Portion Portion Tip
Portion Portion Portion Inst. File Length Length Length Diam. Diam.
Diam. Diam. No. (L.sub.1 + L.sub.3 + L.sub.4) (L.sub.1) (L.sub.4)
(L.sub.3) (D.sub.1) (D.sub.2) (D.sub.3) (D.sub.4) Taper 70a 25 mm 5
mm 15 mm 5 mm 0.10 mm 0.20 mm 0.50 mm 0.50 mm 0.02 70b 25 mm 5 mm
15 mm 5 mm 0.15 mm 0.25 mm 0.55 mm 0.60 mm 0.02 70c 25 mm 5 mm 15
mm 5 mm 0.20 mm 0.30 mm 0.60 mm 0.60 mm 0.02 70d 25 mm 5 mm 15 mm 5
mm 0.25 mm 0.375 mm 0.75 mm 0.80 mm 0.025 70e 25 mm 5 mm 15 mm 5 mm
0.30 mm 0.425 mm 0.80 mm 0.80 mm 0.025 70f 25 mm 5 mm 15 mm 5 mm
0.35 mm 0.475 mm 0.85 mm 0.90 mm 0.025 70g 25 mm 5 mm 15 mm 5 mm
0.40 mm 0.525 mm 0.90 mm 0.90 mm 0.025 70h 25 mm 5 mm 15 mm 5 mm
0.50 mm 0.625 mm 1.0 mm 1.0 mm 0.025 70i 25 mm 5 mm 15 mm 5 mm 0.60
mm 0.725 mm 1.1 mm 1.1 mm 0.025 70j 25 mm 5 mm 15 mm 5 mm 0.70 mm
0.825 mm 1.2 mm 1.2 mm 0.025 70k 25 mm 5 mm 15 mm 5 mm 0.80 mm
0.925 mm 1.3 mm 1.3 mm 0.025 70l 25 mm 5 mm 15 mm 5 mm 1.0 mm 1.125
mm 1.5 mm 1.5 mm 0.025
[0175]
10TABLE 3C Apical Cleaning Instruments (30 mm) Total Abrad. Square
Round Abrad Square Shank Length of Portion Portion Portion Tip
Portion Portion Portion Inst. File Length Length Length Diam. Diam.
Diam. Diam. No. (L.sub.1 + L.sub.3 + L.sub.4) (L.sub.1) (L.sub.4)
(L.sub.3) (D.sub.1) (D.sub.2) (D.sub.3) (D.sub.4) Taper 70a 30 mm 5
mm 20 mm 5 mm 0.10 mm .20 mm 0.60 mm 0.60 mm 0.02 70b 30 mm 5 mm 20
mm 5 mm 0.15 mm 0.25 mm 0.65 mm 0.70 mm 0.02 70c 30 mm 5 mm 20 mm 5
mm 0.20 mm 0.30 mm 0.70 mm 0.70 mm 0.02 70d 30 mm 5 mm 20 mm 5 mm
0.25 mm 0.375 mm 0.875 mm 0.90 mm 0.025 70e 30 mm 5 mm 20 mm 5 mm
0.30 mm 0.425 mm 0.925 mm 1.0 mm 0.025 70f 30 mm 5 mm 20 mm 5 mm
0.35 mm 0.475 mm 0.975 mm 1.0 mm 0.025 70g 30 mm 5 mm 20 mm 5 mm
0.40 mm 0.525 mm 1.025 mm 1.1 mm 0.025 70h 30 mm 5 mm 20 mm 5 mm
0.50 mm 0.625 mm 1.125 mm 1.2 mm 0.025 70i 30 mm 5 mm 20 mm 5 mm
0.60 mm 0.725 mm 1.225 mm 1.3 mm 0.025 70j 30 mm 5 mm 20 mm 5 mm
0.70 mm 0.825 mm 1.325 mm 1.4 mm 0.025 70k 30 mm 5 mm 20 mm 5 mm
0.80 mm 0.925 mm 1.425 mm 1.5 mm 0.025 70l 30 mm 5 mm 20 mm 5 mm
1.0 mm 1.125 mm 1.625 mm 1.7 mm 0.025
[0176] To ensure that the files have an appropriate working length,
it may be necessary to place stops around the shank portions of the
files identified for example at 76. The practitioner then selects
an instrument from set 70 shown in FIG. 1 and detailed in Table 3B.
After selecting an instrument, the practitioner then determines,
based on feel and experience, whether the file is appropriately
sized or whether a larger or smaller file is needed. For instance,
if the practitioner selects instrument number 70b which has a tip
diameter of 0.15 mm and the file binds after insertion, then the
practitioner would switch to instrument number 70a which has a tip
diameter of 0.10 mm. Similarly, if instrument number 70b is too
loose then the practitioner would then switch to instrument number
70c which has a tip diameter of 0.20 mm. The practitioner then uses
that appropriately sized instrument to clean the apical portion of
the root canal by hand. If the practitioner concludes after using
an appropriately sized file, that further instrumentation is still
needed within the apical portion then the instrument with the next
largest file may be used. It is typically unnecessary to use a
third instrument with an even larger file after using a series of
two instruments. However, the practitioner may clean the apical
root portion with a series of more than two instruments as deemed
necessary by the practitioner in order to fully clean the apical
portion. This procedure is preferably followed until an instrument
has been used that has an abrading portion with a taper that is
greater than 0.20 such as instrument 70d. Abrading portion 79d of
file 74d has a taper that is 0.025. If file 74d is the first file
inserted into the root canal then it may be necessary to utilize
one or more files with larger tip diameters that also have abrading
portions with a taper of 0.025.
[0177] After the apical portion of the root canal has been cleaned
with the set shown at 70 in FIG. 1 and as detailed in Table 3B, the
root canal may appear as does root canal 252a' shown in FIG. 6D
with a cleaned apical portion 264. More particularly, after use of
an instrument or instruments, apical portion 264 may appear as
shown in FIG. 6D. Note that cleaning apical portion 264 has
substantially widened the bottom half of apical portion 264 while
the top half is less significantly flared when compared to its
appearance before being cleaned. The appearance of apical portion
264 results from the use of increasingly larger abrading portions
to widen and to clean the apical portion.
[0178] Set 10 and set 40 are preferably disposed after use.
However, since only one or two instruments from set 70 are used, it
is preferable to replace or clean the instruments used from set 70.
All of the sets of instruments described in this example may be
sold together as a comprehensive kit or various sets may be grouped
together as kits intended for use with teeth of particular lengths.
For example, the sets used in the tooth cleaned in this example
which are detailed in Table 1B, 2B and 3B may be sold together.
Additionally, since set 10 and set 40 are intended to be single use
sets these sets may also be sold together as a single use
disposable kit.
Example 2
[0179] This example describes an exemplary system for cleaning a
root canal without abrasively cleaning the apical portion. The
apical portion is cleaned after the operative middle portion has
been cleaned with set 10 as set forth in Example 1. Access into the
apical portion has been improved through the use of set 40 as
described in Example 1. Cleaning of the apical portion is then
initiated by inserting a cleaning instrument into the apical
portion as shown in FIGS. 5A-5B and delivering irrigants. The
cleaning instrument is a cannula 360 of an endodontic irrigator tip
320, as previously described in reference to FIGS. 5A-5B. After
syringe 390 has been used to deliver irrigants into root canal
254b, the irrigants and any remaining debris are removed by
aspiration via irrigator tip 320 coupled to an aspirator.
[0180] Note in addition to set 10 and set 40 being disposable after
use, irrigator tip 320 is also preferably disposable. Note also
that instead of a large set of instruments like set 70, only a
single irrigator tip need be used so it is much less expensive to
merely irrigate. It is also less time intensive since it is not
necessary to use a series of apical instruments. All of the
instruments described in this example may be sold individually or
together as a comprehensive kit.
[0181] The present invention may be embodied in other specific
forms without departing from its spirit or essential
characteristics. The described embodiments are to be considered in
all respects only as illustrated and not restrictive. The scope of
the invention is, therefore, indicated by the appended claims
rather than by the foregoing description. All changes which come
within the meaning and range of equivalency of the claims are to be
embraced within their scope.
* * * * *